Hi all,

Can anyone come up with a plumbing diagram that will allow me to use my RO systems waste to fill the toilet cistern, but bypass the RO unit when its own tank is full or the cistern needs filling?
My mind just can't get around the float valves and what not necessary...
http://img232.imageshack.us/img232/2872/56529701.jpg

Not a bad idea. RO systems waste lots of water.

Anyway, you drew it correctly: Black plastic tube is the RO's waste. Run it to the toilet tank instead of sink drain. If RO system supplies more water than toilet tank can hold, water will overflow to the bowl through the overflow tube.

Let's see what other Experts have to say...

I know absolutely nothing about this subject, but I have an opinion anyway.

Not a bad idea. RO systems waste lots of water.

Anyways, you drew it correctly: Black plastic tube is the RO's waste. Run it to the toilet tank instead of sink drain. If RO system supplies more water than toilet tank can hold, water will overflow to the bowl through the overflow tube.

I think he could probably lower the height of the ballcock in small increments until he finds the right balance between inflow of the RO system and overflow through the overflow tube in the WC.

I'm installing a BRAC tank (http://bracsystemswnw.com/page3.php) on a job here in Seattle that recycles the water from 3 showers and 1 soaking tub for flushing the homes 3 WC's. I am also tasked with finding a way to reclaim the waste water from a water softener and RO system situated in an adjacent building and pump it into the BRAC tank.

The distance is about 200 feet -- 140 feet of that distance is below grade where I installed 1-1/2" PEX tubing during the groundwork phase.

I'm thinking about pumping it with a Little Giant Drainosaur (http://www.little-giantpump.com/drainosaur.htm) to the BRAC tank -- Any comments about the feasibility of this plan, Milo?

Thanks guys!
Milo, I've got it set up like that currently actually - but I'm trying to find a way to minimize all the waste that's dribbling out the overflow. Water costs are extortionate here - that and save the environment and such.

hkstroud, I'll give that a go this weekend and report back!

I too know nothing about what you are doing but like Harold also have an opinion. Lets think about how this will help. Toilet tank is full 24/7 until you flush. If your system back washes that watyer enters the tank, which is full, and just goes to over flow. If you shut off the supply to the tank and rely only on the RO then you can only flushonce until the RO back washes again. Did I miss something here because I do not see how this is going to be efficient. If my buddies have another read on this please tell me how this will work. Thanks guys

Perhaps I miswrote what I was trying to achieve?

When the toilet is flushed and cistern is emptied, I want the RO unit to start filtering water to it's holding tank and draining its waste to the cistern (it is more than capable of filling the cistern before its next use).

Except when the RO units filtered water holding tank is full, I want the cistern to fill from the mains.

hkstrouds diagram should do this quite nicely, due to the pressure reducing valve located on the mains line to the cistern allowing preferance of pressure to the RO unit (and its storage tank).

Once the RO units tank is full, (I'm pretty sure) it automatically stops filtering which will cause all water to bypass the RO unit and flow through the restrictor mentioned above?

The only thing that I'm not sure of is if the gravity fed water from the 'waste storage tank' will out perform the flow restricted input from the mains, or if I will need to put a pump from the 'waste storage tank' to the cistern.

As previously stated, I know nothing about these systems. My suggestion is based on the assumption that the waste line is under pressure. The waste water holding tank is a pressure tank. When waste water is forced into the tank by the line pressure the air in the tank is compressed, therefore the line to the toilet is under pressure.

All depends on IF the waste line us under pressure between the membrane unit and the flow restrictor. I assume that the flow restrictors purpose is to prevent the incoming water from just flowing through the system and coming out the waste line. Logic says that without it, there would be not any pressure at the faucet.

I am also assuming the shut off valve is some how activated by the pressure in the filtered water storage tank. If not, why have the tank.

I'm with you - there'd have to be pressure after the membrane, there's nowhere else for the mains pressure to go?

I had a bit of a mind blank as I was writing that last reply. I figured you were using a second pressurised tank to collect the waste and forwarding it to the cistern, but I was thinking of how to set it up as a gravity fed system at the time and replied with my half thought out plan in mind :rolleyes: