If you’re building a new house, or doing a full plumbing remodel, you may want to combine all your greywater into one line, and then have a collection tank and pump to distribute it more widely to your landscape.

In retrofit situations it doesn’t usually make sense to combine all the greywater pipes together because it can be very costly. Usually it’s more practical to do each fixture separately and use that water to irrigate the area closest to the fixture.