Hi All,
Recently we moved into a new house that is solely dependant on tank water. The house, tank and rainwater collection system are approx 40 years old, without much improvements since first constructed. i.e. It's a simple gutters into down pipes and then straight into the tank without any 'first flush' devices, strainers filters or anything except for a half decent 'gutter guard' mesh.
When we first moved in we had the water tested, and it came back quite bad, so we had the tank professionally (?) cleaned and sanitised, and I installed a 'whole house' filter system. But even with a 1 micron filter the water looked like weak 'tea' and tasked like dirt! After several months it never settled, so I started reading up on ways to improve our water supply.
A lot the information I found was contained in these forums, so I thought I'd share some of my experiences ect.
I'm still a long way from completing everything I plan to do, so this is just the beginning and everything I am doing is somewhat experimental and open for design changes if needed.
I started by installing a triple 20" x 4.5" filter system, which helped a lot, but far from great. The tank water was very cloudy (bad turbidity). You could only see into the tank water about 200 or 300 mm deep. I spent days (on and off) vacuuming the tank with a pool pump and filter setup to try to clear the water, leaving the pump on to recirculate the water through a filter when I wasn't there myself. I eventually resorted to using a potable safe flocculant chemical (polyquaternary amine) and filtered this out which worked very well. Now I can see the bottom of the tank easily, but wasted many kilolitres doing so.
Now my next big mission is installing a first flush sediment trap in the feed pipe to the tank. This is currently a job in progress.
The trap I'm building now is mostly from the designs of 'Diver' on this forum.
Refer the following post for a lot of info: http://www.ata.org.au/forums/topic/45691
If it works, all credit to him.
I'll try to keep this post shortish, But this is what I have.
There is approx 200 to 220 square meters of roof catchment, which go into many down pipes, and eventually into a single 150mm DWV pipe straight to a 100000L concrete tank. The house is several meters higher than the tank so the main feed pipe is a dry system, and underground except the last 10 meters or so (see photo).
My modification is to incorporate two traps in the last section of the pipe as per Divers design. Diver only had the one trap but I wanted two just to increase the 'first flush' capacity. This may be a waste and I can remove parts if it is apparent there is no need or it. Two 'Y' junctions make the two traps, one down as a primary trap, and one up. The second 'up' trap uses the height to separate contaminates with the clean water travelling up the second trap and into the tank. This creates a large (ish) trap area that fill up several meters before the first trap junction before enough water height is obtained to rise up the second trap and spill into the tank. I also wanted the extra height above the tank that the second trap gives me for another reason I'll go into later, if it works.
The traps feed pipes and reducers eventually down to 40mm dwv, then into two separate irrigation valves on timers set to dump the trap waste water each day. A manual ball valve will also be plumbed in parallel to the valves for manual dump if required. I'll plumb the ball valves and irrigation valves horizontally to prevent sediment settling on the valve seals, but I'm still not sure how these valves will cope over the long term.
This system uses the Laminar Flow principle, which Diver explained well in the other post. It hopefully should be well suited to our situation as there is a long run of almost 15 meters of straight pipe before the first trap, and after flushing, will remain a dry system.
At the moment I've only laid the horizontal main sections as see in the photos. Hopefully have more info and pictures later.
