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Drinking tank water

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Started 10 years ago by tom
Latest reply from saferain

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tom
Member

We will be building a house in Melbourne suburbs and are planning on putting in an underground 20,000 litre tank. Including verandas and garage we will have around 280-290m2 of roof area, and there will be just me and the wife (kids maybe...) I was hoping we could install a filter/purifier (??) so that it supplies the entire house and we can actually drink the water, as apposed to the usual plumbing to the toilet only. Has anyone done this? What would I need? Is it possible to have something that detects when the tank is empty and then switch to town water? Or even detect the tank water quality has become that bad it can't be purified?

Any help is appreciated.

Posted Wednesday 14 Dec 2011 @ 9:16:48 pm from IP #
8688john
Member

Hi Tom,

Your aim is very much achievable. We are currently also building in the Melb suburbs and will be set up for ‘whole of house’ tank operation, with switch over to town supply when/if necessary. Our roof area – also house, veranda & garage – is similar but we will have 50,000 litres or more storage.

To keep the maths simple, let’s assume your roof area is 300 square metres and the annual rainfall is 500mm. Ignoring losses, the annual collection is therefore 150,000 litres.

When you have been on tank water for a while you will become more economical with it but, as a starting point for estimation, you could allow 100 litres/person/day. If your goal is to be independent of the mains water, you also need an allowance for gardening.

The ATA provides a tank sizing estimator at http://tankulator.ata.org.au/

In setting up your system you need to consider screens, strainers and first flush diverters to keep animals, insects and debris out of your tank. With basic precautions in place from the start, you will have great water and you wont need the nuisance of in line water purification. Here is one place to look for first flush diverters etc http://rainharvesting.com.au/

Posted Wednesday 14 Dec 2011 @ 10:11:13 pm from IP #
Catopsilia
Member

I can't be much help, tom, but I'll say what I have done.
I'm in a small country town. I have a town connection, but it goes only to one tap and to a filling pipe above a tank for emergencies.
I have three 10,000 litre polyethylene tanks, fed from about 100 square metres of colorbond roof through a large (150 mm) underground siphon. Annual rainfall is 650 mm, but much less reliable than in Melbourne.
The tanks are above ground, and I can read the water level through clear plastic pipes plumbed to the outside. Unfortunately, algae grow in the sunlight, making the level hard to read. I should disconnect them and clean them out.
I once ran one tank dry, but then I just switched to another. One of the three tanks has remained full for years.
I added town water in the first month, but never in the twelve years since. I frequently have to open a siphon (on a hillside) to allow excess rainwater to drain into the garden. It doesn't run off the block. This action keeps the siphon pipes reasonably clean.
I don't use any filter. I don't think I am very likely to catch bird-flu. The water tastes good to me.
Regulations about water use are to protect the Council far more than to protect the person drinking it. I was perhaps fortunate to get my system going before the Council became paranoid.

Posted Wednesday 14 Dec 2011 @ 10:23:01 pm from IP #
Catopsilia
Member

While I enjoy having my own rain-water supply, it must be said that it costs a LOT more than town water.
I am amazed that so many people have let themselves be bulldozed into installing very expensive tanks and pumps. Then not to be allowed to drink it!

Posted Wednesday 14 Dec 2011 @ 10:32:43 pm from IP #
Diver
Member

There are a lot of issues here but here is an overview.

A 20,000 litre storage is very small when you are talking about a total house supply. Your harvest area may also appear large but don't be mislead by various web site claims that 1 sq m X 1mm of rain = 1 litre. Rain harvesting IS NOT 100% efficient, it is closer to 85% maximum but usually a lot less. This reduces every 100mm of rain on 280 sq m from 28,000 litres to 23,800 litres maximum. An average year's rainfall would supply an average targeted use (150 litres per person per day) 2 person Melbourne household but no more unless you had a wet year.

You mention supplying the entire house but also mention a mains back up supply. If you have a mains water supply passing the property, you will be charged service fees regardless of whether you use the water or not. You also cannot cross connect the mains supply with a water supply collected onsite unless you have plumbed a number of provisions to prevent back flow. This is why tanks connected to a laundry for example are plumbed to a third tap. There are also a number of other regulations to consider, plumbing, Vic Health etc and you need to know what these are before you decide on what you would like to do.

Mains back up devices are expensive and why would you want to partially refill a tank with water delivered under mains pressure to then use a pump to supply the house? Some back up devices also use some mains water to prime the pump every time the pump is used.

The submersible pump will have a float sensor that cuts the motor if the level drops and you can also have a separate tank level sensor fitted. Some people even wire the level monitor to their PC!

There are too many issues to go into here but perhaps you could consider supplying only the toilet(s), laundry, hot water service and an outside tap.

Under ground tanks and bladder tanks in particular need very good prior filtration and a lot of systems that have stagnated have been difficult to clean. If you have a truly professional installation and a good pre and post tank filtration system, you will have top quality potable water. A first flush diverter on its own just doesn't cut it.

Potable consumption is only a few litres per day and you could have this by keeping a jug (filled from the laundry) in the fridge. Filtration can be by a 2 stage cartridge and UV system for optimal results. There is plenty of info online.

Posted Wednesday 14 Dec 2011 @ 10:39:07 pm from IP #
Diver
Member

Catopsilia said:

The tanks are above ground, and I can read the water level through clear plastic pipes plumbed to the outside. Unfortunately, algae grow in the sunlight, making the level hard to read. I should disconnect them and clean them out.

Get some poly pipe, split it down the middle and put it over the clear plastic pipes. When you need to check the level, just turn the split section outwards to see the level.

Posted Wednesday 14 Dec 2011 @ 10:58:59 pm from IP #
Catopsilia
Member

Thanks for the tip, Diver!

Posted Thursday 15 Dec 2011 @ 12:59:19 am from IP #
cava
Member

Diver said: If you have a mains water supply passing the property, you will be charged service fees regardless of whether you use the water or not.

Not totally correct. It is covered under the Trade Practices Act (Commonwealth legislation, which overrides state legislation) which effectively states that no one can be forced into a contract against their will. The water suppliers, even though generally owned by the state government, are registered as private companies and you cannot legally be compelled to do business with them.

The problem is, that they will hassle you and effectively bluff you into believing that they are empowered into charging you their usual supply fees etc.

Also, just for the record, we live on the Mornington Peninsula and have a 23,000 in ground tank that we use for all our needs and have never run out of water since it was installed (3 years??). However, we also have town water supply, that we pay for, as a just in case insurance policy. When we get another tank of similar size, we will stop paying for the town water supply fees.

Posted Thursday 15 Dec 2011 @ 6:48:38 am from IP #
marie
Member

I think you also have to use UV sanitation in conjunction to your filter. That's what I had found when I researched this a while ago. With the price of water tanks I found prices have gone down considerably over one year. Does anyone found that too? For instance when it used to be about $1/Lt, I have had a quote for an underground concrete water tank 22000Lts for $7000, installed.

Posted Thursday 15 Dec 2011 @ 7:26:29 am from IP #
yabbietol
Member

You city people amuse me. Tank water can be drunk many people throughout rural Australia drink it all their lives. If in all new developments each new house was required to have at least 20,000 litres in rainwater storage for domestic use many of our water problems caused by new developments would be over. If we could get all Australians to have at least 20,000 to 40,000 litre tanks on their existing houses for domestic water, where feasible, much of our environment would be protected from the need to dam rivers and environmental flows for rivers would not be less an issue. The key historical problem is water quality, with modern tanks this is much less a problem.
Rainwater across Australia is generally potable unless you live next to a lead smelter or similar emitter of toxins. A minor problem is giardia and similar bugs carried by bird pooh. This is easily dealt with by using quality filtering. A pre filter of 5 microns and a 1/2 micron ceramic final filter will filter out bacteria and spores making your water totally safe (if you maintain the filters every few months). UV sterilisation is expensive both in installation and running costs and can be unreliable if the lamp fails. Quality multi-stage filtering is more reliable (filters need cleaning water flow slows) and minimal running costs.
Tank water saves energy and the need for much infrastructure, it is also nice to drink as it is not treated with chlorine or flocculates. Many people just drink it without any treatment and do not seem to have health problems.

Posted Thursday 15 Dec 2011 @ 8:20:38 pm from IP #
tom
Member

Thanks for the all replies.

I had done some research prior to posting, and I'm unsure whether councils/yarra valley water will allow you do what I want. I have no issue drinking the water, but if I can't plumb it to the kitchen, then that's unlikely to happen. It's only a small amount in comparison to toilets, showers, washing & outside usage, but still I'd like the whole house as self-sufficient as I can make it. Same reason I will be spending extra $$$ on double/triple glazing, excessive insulation and solar panels. I know I won't get the money back in the end, but at least I will be satisfied I've made some trivial contribution to the environment. And with prices of energy and water heading north, maybe I will get the money back.

So, it sounds like 20,000 won't cut it? This sounded like a nice round figure based on our current consumption of 230-250L a day. We're not likely to have 3 kids, but if we did I'd hope we could manage to keep the usage around 600L a day, so multiplied by 31 days in a month gives 18,600. So 20,000 sounded good. I assumed enough storage for a month of no rain. Also I'm not sure we can sink a tank any bigger under our driveway. Our driveway is only 5.3m long, and tapers to a 3.5m crossover. I assume there are limits about how close to boundaries and the house you can excavate. I had been advised the tank should be closest to the drainage point of the block, hence why under the driveway rather than in the backyard which has more space. Backyard is also restricted by existing large trees (roots!) that the council is unlikely to let us remove.

As for filtering, I had assumed I'd need something like a first-flush diverter, maybe an inline pre-filter before the tank, then a 2 stage (5u, 1u) post filter in series with a UV steralizer. Have also read you need to put a small amount of chemical in the tank to stop nasty things growing. Lost the link for this one, so not sure.

Again, appreciate the response.

Posted Thursday 15 Dec 2011 @ 9:05:00 pm from IP #
ghostgum
Member

Before the tankulator tool was available, I built a house and put in 10000 litres of rain water tanks om Melbourne. We use this for washing machine, toilets and garden. I downloaded the last year of rainfall data from the Bureau of Meteorology website. I then found the pandora archive site and managed to get three more years of data. I used this to estimate how much water we could draw from the tanks each day without ever running the tanks empty. 10000 litres will run empty in Melbourne if you get a 2 month long dry spell in January/February, assuming 200 litres use per day. 20000 litres will be better, but you will still need to watch your usage. 50000 - 100000 litres averages over an entire year, and is a better size, but it doesn't fit well on a suburban block.

Our overall usage is about 400 litres per day, of which half comes from mains, and half from the tank. We have water efficient toilets, water efficient showers and taps, and a very water guzzling top loading washing machine. We have 2 adults and 2 children, and we aren't trying hard to conserve water.

If you did install 20000 litres, then once in 10 years you may need to get a water delivery by truck.

Are you planning to use septic or the sewerage system? If sewerage, then you will still be paying bills to the water authority.

Posted Friday 16 Dec 2011 @ 5:38:09 am from IP #
Diver
Member

There have been numerous studies over the years on urban watertank water quality that have consistently and conclusively shown that for the majority of tanks tested, the water has failed to meet potable standards and many have tested positive for high % free floating metals. There is a large amount of research information readily available from various universities (at a fee). Comparing country to city is a folly.

Re tank size, lets not forget that a tank of any size starts empty! Statistics may be well and good but each individual household will be different even if roof size, location and occupants are the same. What ghostgum has said is the key, do your own maths to be the wiser. For practicality and continuance of use, it may be wise to build up a reserve before tapping the supply if also connected to mains. If using a submersible pump, it is wise to also calculate the level at the float cut off point as this is effectively the 'empty' mark.

Posted Friday 16 Dec 2011 @ 7:00:37 am from IP #
Diver
Member

tom said:
Have also read you need to put a small amount of chemical in the tank to stop nasty things growing. Lost the link for this one, so not sure.

Is this it?

http://www.davey.com.au/ApplicationandProducts/Acquasafe_Rainwater_Purifier.aspx

If you are able, use a sediment pit for the final filter pre tank. The one commonly available would be too small for your proposed set up but I will PM you a link for a particularly good one that you could DIY if you have a suitable location. It would be cost effective.

Posted Friday 16 Dec 2011 @ 8:42:02 am from IP #
Solgen
Member

We live in Sydney and 3 years ago we put in a 10000l tank which was the biggest I could fit, it is fed off 100m2 of roof. The tank supplies all our water except for a mains connection to the kitchen, it will also changeover to mains supply for the rest of the house when the tank runs dry.
In the three years we have only had to run main supply for the whole house for a total of 30 days. The tank has enabled us to reduce our mains water from 82kL pa to 5kL pa. I estimate that our two person household uses about 180l per day.
We only water our vegetable garden, the rest is local flora which doesn't get watered. I haven't had the water tested but to date have not noticed any issues although we don't normally drink except when cleaning out teeth! We have a whole of house filter (Big Blue) which is much better than the small filter installed by the plumber.
I think if we could have fitted a 15000l or 20000l we would not need a mains backup. 10000l allows about 2 months without rain which for Sydney is mostly OK, our annual rainfall is 1000mm.

Posted Friday 16 Dec 2011 @ 10:58:59 am from IP #
cava
Member

We use our tank water exclusively for everything including showering, cooking, drinking and the vegie garden without reservation. Had the tank tested about 4 months ago by ALS Laboratory Group for a full spectrum analysis. Everything was OK except for a count of 3 for E.Coli. We did not have any health issues, however the limit according to health and water authorities is effectively 0 especially for sick, elderly, children etc.

Had silver coins suspended in the tank for sterilisation, which probably accounted for the low E. Coli count despite the many birds that use our roof area as a meeting venue and toilet.

Personally, I just think that the suppliers are frightened by legal issues, and of course they want you to continue using their water product rather than being independant etc but thats a different issue.

Posted Friday 16 Dec 2011 @ 12:41:01 pm from IP #
Lance
Key Master

Actually, have to agree, here in the new place in Tassie we are running purely on tank water, although most of that water is coming from a bore, but when it rains all the crud on the roof gets washed into the tank. We notice some degree of particulates coming through so all drinking and cooking water goes through a jug filter to remove that, but it doesn't remove bacteria as far as I know.

When brushing teeth I use water from the hot water tank as the heat kills the nasties, if there are any, but for showering etc a lot of the water is via the cold tap with no treatment.

We have noticed no problems at all here in 6 weeks of use, would have thought any issues would have shown themselves by now, so I suspect that the very low ecoli etc requirements are indeed mostly to make the authorities feel good.

Remember, like all creatures on this planet, humans evolved to deal with bacteria and viruses, indeed we need a low level exposure to them to maintain a healthy immune system...

Posted Friday 16 Dec 2011 @ 11:13:22 pm from IP #
tom
Member

Thanks for all the replies, much appreciated.

I swim in a public pool a few times a week and thinking about what I'm occasionally swallowing there, I guess worrying about the quality of tank water probably is a wasted concern. When I first started swimming I got sick - colds, flu, nausea - but now I don't get sick at all, so I guess it's just a case of HTFU as Lance says.

Posted Sunday 18 Dec 2011 @ 8:38:45 pm from IP #
Diver
Member

It all comes back to the quality of the individual's harvested water and its end use. Given the high incidence of lead and other heavy metals plus microbal contamination found in tanks during many studies on this subject, people should not be dismissive of those who exercise their individual rights by choosing to safeguard their health.

A lot of households also choose to have under sink filtration on their mains water. Others also wash fruit before eating, check packaged product ingredients before purchase and wear a hat or apply sunscreen when outdoors. The list goes on. Does HTFU also apply to them? For others, ignorance is bliss.

Posted Sunday 18 Dec 2011 @ 10:07:39 pm from IP #
pulpo
Member

Just out of Goulburn NSW have built a house, council requirement 50,000L rain water tank and 10,000L for fire fighting.

For 2 people never come close to running out, that includes watering the garden.

50% of the residence in the area have filter and 50% have nothing on the supply line.

Trying to get clean water in is also important.

I product like tank vac looks pretty impressive.

I have the large blue filter.

Good luck

Pulpo

Posted Monday 19 Dec 2011 @ 6:32:19 am from IP #
gazmo88
Member

"A product like tank vac looks pretty impressive."

Yes but at $260 it looks a bit expensive for what seems little more than a few pieces of plastic pipe.

Appearances can be deceptive however.

Has anybody here actually tried one and if so would they like to comment on the efficacy ?

Posted Monday 19 Dec 2011 @ 10:50:18 pm from IP #
peter69_56
Member

I am a little stunned by peoples fear of drinking tank water. I lived on a farm and all we had was tank water, and if that run dry on a hot summer, hand pump it into tankers and then hand pump it into the tanks. We never had any fancy filters, divirters or anything. never had anything wrong with us relating to tank water.

It just seems to me as a society we are becoming paranoid about germs and the big companies have us fooled thinking unless it has been cleaned, irradiated, de-germed, bleached and boiled it might just give us the black plague. I dont generally use all types of disinfectant and such on kitchen benches, just hot water and soap and then let it dry. The companies would have us believe that unless we use bleach we will die.

In all reality the water probably made my immune system all that much stronger, similar to natives where if us white folk were to drink the stream water we would break out in a bad case of the runs.

Be sensible, take out the leaves and rubbish by a gutter strainer and accept the water is ok, probably better for us than the chlorinated, flourinated water we receive from the system never mind the desal plant, I have tried that water and it tastes dead.

Just be sensible, not paranoid.

Posted Monday 19 Dec 2011 @ 11:26:58 pm from IP #
gazmo88
Member

"never mind the desal plant, I have tried that water and it tastes dead"

We lived on a boat for a couple of years and drank mainly desalinated water. In our experience it was sweet. Everybody liked it. The output of a properly configured desal unit is 2 "Os" and one "H" and _nothing_ else.

When I lived in the bush on unfiltered tank water I also found that quite sweet.

So I suspect if you do not like the desal plant water its not how its made but what they do with it after its made.

The question of whether or not a city like Sydney should have a desal plant is a very different issue however

Posted Monday 19 Dec 2011 @ 11:43:11 pm from IP #
peter69_56
Member

The desal was done at a resort in Indonesia, Wakatobi. Whatever they did the water was so bad that we could not drink it. We used bottle water. maybe they take everything from it instead of leaving a little salt in it. natural water does have some minerals in it. If you desal to 100% pure maybe you take aout all the taste, or maybe they were not delalling it properly and leavuing a lot of salt in it.

In any regard it was bad. I will take tank water any day, no filters, no carbon filter, no clorine, just pure tank water

Posted Tuesday 20 Dec 2011 @ 9:32:14 am from IP #
yabbietol
Member

If you run tank water through two or three filters staring with a coarse filter for the lumpy bits followed by a 5 micron (replaceable and usually disposable) and a .5 micron ceramic filter (cleanable and lasts for several years) you will end up with bacteriological safe water including no giardia. This type of set up will cost a few hundred dollars and require replacement filters (5micron about $50) about every 6 to 12 months and replacement of ceramic filter (Royal Dolton about $90) every few years. It will still taste like water, no other treatment should be necessary unless the rain water contains dissolved salts or organic toxins. I have used this type of filter system on my tank water which is my only domestic water supply for about 9 years. Prior to that we drank the tank water with no treatment and fitted the filter system after a couple of bouts of giardia, which have not occurred since the filter system was fitted.
Dissolved salts could come from industrial pollution such as that caused by metal smelting or organic solvents and toxins could come from engines or industrial activity such as petroleum refining. If you live away from heavy industry and filter the tank water it should be safe to drink.
Desal will remove salts, but depending on the process may not remove some organic toxins such as dioxin. Tank water is generally safe to drink, filtering to sub micron level removes all bacteriological hazards and makes for pleasant tasting and safe water. Note, UV tank water sterilisation is unreliable and expensive to run.

Posted Friday 23 Dec 2011 @ 8:53:26 pm from IP #
Diver
Member

Some desalination processes remove a lot of oxygen from the water and this ruins the taste.

The vast majority of water tank installations I see are sub standard and amateurish to the extreme. One of the biggest mistakes is when the outlet supplying the pump is fitted at the bottom of the tank. This draws water from the anaerobic (lacking oxygen) zone and is the worst quality water. It also ingests sediment into the pump and is a cause of pump failure.

Another huge mistake is when the tank's top meshed inlet is fitted directly above the outlet. The inflow then stirs up the sediment layer around the pump. This results in sediment resuspension which also releases lead and other particles locked away in the sediment layer. Not the best time to be drinking unfiltered tank water!

The best system is to have two tanks and direct all inflow to the first tank. Use this tank as a settling tank and slow feed the decanted water to the second tank supplying the pump.

There are also several ways to easily, quickly and cheaply make a very effective sediment trap and having good quality water on demand is not difficult.

If using a first flush diverter, never ever fit it to the top of the tank's vertical riser on a wet system. The flushing velocity required to flush the pipe will never be achieved and this will leave decaying organic matter in the pipe. This can turn stagnant and pollute the incoming fresh water diverted to the tank the next time it rains.

Posted Friday 23 Dec 2011 @ 11:40:21 pm from IP #
cava
Member

yabbietol said: This type of set up will cost a few hundred dollars and require replacement filters (5micron about $50) about every 6 to 12 months and replacement of ceramic filter (Royal Dolton about $90) every few years.

Where do you source the ceramic filters from? We are in Melbourne.

Posted Friday 23 Dec 2011 @ 11:58:43 pm from IP #
yabbietol
Member

Sorry I do not know where to get the ceramic filters in Melb. I live in NSW outside Canberra and can pick them up at a couple of water filter specialists in the ACT.
Royal Doulton is a well know company and I believe you may be able to get them from water filter specialists in Melb. The filters cost about $90 and fit the standard under sink filter holder. They are easily cleaned with a standard nylon scourer. This cleaning abrades away a bit of the filter each time and eventually they become too thin and break while cleaning (we keep a spare).
Good luck in finding them as they last quite a long time and are good value in the longterm.

Posted Sunday 25 Dec 2011 @ 9:37:40 am from IP #
cava
Member

Thanks Yabbietol.

Posted Sunday 25 Dec 2011 @ 10:19:24 am from IP #
macklinvinger
Member

For generations, those of us who live in urban areas have enjoyed high-quality town
water. Sourcing water from publicly-funded dam projects, this system was introduced to
overcome public health problems in previous centuries, and has been highly successful.
In these early years of the 21st. Century, some things are changing. A more
environmentally-aware population is increasingly concerned about the environmental
effects of building new dams. At the same time, governments are less willing to take on
the borrowings, or impose the huge tax bills involved in major works. Happily, there is a
groundswell of opinion in the community that we should all take more responsibility for
reducing our water use- capturing what we can, and re-using our waste water. A huge
increase in interest in water tanks has been one result.

Posted Saturday 31 Dec 2011 @ 10:04:37 am from IP #

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