According to the Arizona Daily Star, all new homes built in Tucson, Ariz., after mid-2010 will need to include plumbing for a greywater system. The new rules require stub-outs for greywater systems for all new homes that are issued permits after June 1, 2010.

The regulations affect only new construction, not existing houses, unless the homeowner builds an addition with a new bedroom, bathroom and kitchen. A newly constructed guesthouse on an existing property would need the greywater plumbing.

Installation of a greywater pumping system is not required, only the plumbing so the bigger system could be installed later.

Builders would be required to install pipes and other plumbing hardware to collect the greywater. A separate set of pipes would be required to take water directly from washing machines to yards.

The greywater plumbing would cost $500 to install - although home builders can knock off $200 of that through a state income-tax credit - and the cost would likely be passed on to home buyers. Homeowners then could choose to install additional pipes, underground tanks to store the water and a pump to move the water outdoors.