If top up from mains is required (advisable, in case rainwater not sufficient), an indoor tank is needed and it must have an ‘air gap’ (plumbing regulations don’t allow a non-return valve).
The indoor tank must be high enough above the toilet cistern to allow the water to fill the cistern by gravity.
An electric pump to take the water up to the indoor tank (and to the tap for garden use).
PROBLEMS Click here to see problems we had with the work, and here to see problems with the dual-flush toilet.
The large 2,700 litre water tank (for collecting rainwater) before it was buried under the drive. We now collect rainwater from the rear section of the drive plus parts of the house roof and the garage roof.