(Back to Case Studies)
Garden Size vs Graywater Volume.
In this example, 3 people live in a house with total garden and unoccupied land space of 30,000 square feet, with good quality loam and reasonable drainage.
The total amount of water required each month to irrigate the entire property is 2 gallons per sq ft = 60,000 gallons per month.
The residents generate 3 (people) x 25 (gallons per day) x 30 (days per month) = 2,250 gallons per month.
Clearly there is nowhere near the amount of water required.
Instead decisions must be made as to where the graywater can be best used - ornamental garden, vegetable patch, trees / fruit trees or a combination of all three.
In this example the ideal irrigated area is 1,125 sq ft.
Multiple irrigation areas supplied at the same time.
A 660W graywater pump can irrigate different areas up to 200' distance from each other at the same time.
The key consideration is how much water is required to fill the supply lines to get the water to the desired location and cause pressurization.
200' of 3/4" supply line can hold approximately 5 gallons of water. If only 5 gallons of graywater was pumped through the irrigation system, the dripperlines would not have sufficient time (or water) to achieve pressurization, which is required for even drip rates.
Although no water is lost, it may not irrigate exactly in the desired manner. 5 gallons is a relatively small amount of water so 200' of supply line generally does not cause an issue.
1,000' of 3/4" supply line however, is likely to cause issues as it can hold 50 gallons of water. This can be managed by proper zoning of the irrigation areas. Re-pumping of water may be preferred in some instances.