Rainwater tank overflow from bottom

kenw1, Jan 8, 3:20am
I want to change our 25,000 litre tank so it overflows from the bottom of the tank, was just going to extend the pipe down into the tank (same diameter 4inch) from the elbow that is presently through the side near the top.

Any other suggestions.

i have seen some systems where they have like a fan of pipe over the bottom of the tank.

Anyone any experience of this system.

Thanks

blans, Jan 8, 3:45am
I would like to know how that could actually work

harm_less, Jan 8, 4:13am
If you have a vertical section of pipe inside and outside (which is what I assume you're planning) don't you then have a potential siphon? Maybe a small 'breather' hole near the top of the outside section of pipe will prevent any risk of self-emptying your tank.

blans, Jan 8, 4:23am
if this can be made to work without loosing all your water its a great way to keep the bottom clean.

rojill, Jan 8, 4:58am
Seems simple enough - just extend the inlet pipe down inside the tank to just above the tank floor. Create a lattice of smaller pipes that lie on the tank floor so that the inlet pipe feeds into them and when the tank is being filled it will stir the bottom of the tank up so that sediment stirred and suspended in the water as often as it rains and will be removed when water is drained from the bottom of the tank, and presumably filtered before use.

kenw1, Jan 8, 5:46am
It appears it does work, and yes it needs a syphon breaker hole.

http://www.tankvac.co.nz/

Am waiting to hear from the maker about installing it in a tank already in use, might have to do a bit of fishing and fiddling to get it in.

Our tank is fine, then suddenly the crud in the bottom starts breeding and ughhh.

daveb, Jan 8, 7:13am
Marley have a system too.

nzjay, Jan 8, 8:17am
A cup full of Janola or household bleach to a tank full will work wonders. You won't taste it.
Repeat monthly over the summer months.
Look at installing improvements to your water collection such as "first water diversion", leaf filters etc.
The roof, with bird droppings and vegetable matter is where the bulk of the contamination comes from.

kenw1, Jan 8, 9:04am
Had a read at the ministries guidelines, and its 1.2l of budget bleach to get an effective level of chlorine and repeat as necessary.

nzjay, Jan 8, 9:29am
Ok, perhaps Janola is a stronger concentration than budget bleaches.
I always used this when my rainwater tank started to grow algae. Kills all the nasties!

m16d, Jan 8, 9:38am
Put a tap in the bottom of the tank. when you've got plenty of water,open it up and let all the stuff that's settled on the bottom drain out.

kenw1, Jan 8, 6:48pm
I always thought janola, but it now has a surfactant added to it, which is why they now recommend the budget bleach, because that is just bleach.

kenw1, Jan 8, 6:49pm
Tanks half underground.

tweake, Jan 8, 9:02pm
did it to the folks water tank.
extended the overflow pipe down to the bottom and across a bit to the lower point. no fan of pipes on the bottom tho, but it still sucks up a lot of the build up.
drill a small hole in the top elbow so it breaks the siphon when the water level drops back down.

rojill, Jan 9, 7:47am
You forgot to mention the decaying bodies of dead birds

nzdoug, Jan 9, 8:06am
you can bbq those.

rojill, Jan 9, 8:12am
and adding the sludge as a tasty sauce.

kenw1, Jan 9, 8:48am
Thanks, why did they not do it when the tank was installed, now got to fiddle about later. Ah well another job to do.

moltenfire, Jan 11, 9:13am
How can that work when the standard outlets are at least 50mm up from the bottom?

moltenfire, Jan 11, 9:19am
My tank has a SS wire mesh basket bolted under the inlet lid which I empty once a year. Last year after 10 years of use, I drained the tank and got inside with a water-vac expecting to find 6" of sludge. There was less than 1/4" of sludge which was a very fine powdery type. Sucked it all out and won't be bothering to clean it for another 10 years. Water is filtered then uV sterilised anyway so it pretty clean - tasted fresher than the chlorinated/flouridated gunge that our friends in town get supplied with. Never did fully understand why man is so intent on poisoning himself. !

bill1451, Jan 11, 9:24am
The way to do it now is have a flexible flexible floating outlet pipe, the other end is still connected near the bottom of the tank but the inlet water comes from the top, so no gunge or less gu ge in it.

nzjay, Jun 16, 1:57am
This. You can buy a floating water pickup as a kitset from somewhere.