"N. Thornton" wrote in message
om...
Grunff wrote in message
...
N. Thornton wrote:

Or you could direct sink waste into toilet cistern, and have your
cistern overflow go down the pan. Reduces water use and avoids the
problem you mention.

I like that idea - but how do you do it when most cistern rims are
higher than the trap? Mount your basin really high?

As long as the top of the water level in the cistern is at or below
the water level in the sink trap it will work. That gives satisfactory
sink and cistern levels in most cases. You cant use this setup if your
sink's below the cistern.

If the water height difference is only small, and the plumbing long,
emptying would be slower, but usually sink is near loo.

Also if you have the trap below the top of the cistern you may need to
drill a hole in the cistern to take the sink pipe. Also some cisterns
have the wrong type of overflow for this setup. So its not as
straightforward as the more conventional setup.

According to folks that have grey water systems feeding the loo
cistern, the detergent content in the sink water increases the time
intervals between bowl cleaning.

If the basin was not used much, the toilet cistern may run out of water. You
need at normal water supply to the cistern in case. Then how do you
prioritise? How do you use fresh water to fill when no grey water? having a
normal ballcock will mean fresh and grey water fill at the same time. You
would need a separate grey water tank.