Fruit trees and vegetable plants grow well with graywater. The risk is that graywater may contain bacteria, and if you eat fruit and vegetables covered in graywater (and therefore bacteria), you may become sick.
If the fruit or vegetable is going to be cooked, any bacteria present will die during the cooking process. This removes the risk.
A substantial crop of tomatoes, irrigated with graywater. Care is required to ensure graywater does not come into contact with the fruit.
An interesting study concluded that tomatoes are not affected by graywater irrigation.
Citrus trees grow well with graywater, however where possible extend the irrigation area beyond a typical mulch basin, to encourage a wider root coverage.
Because the fruit and nuts on established trees are much higher than ground level, there is very little chance the fruit will come into contact with the graywater.
Greywater and vegetables / low fruit
This can be done by bucket (very carefully) but is labor intensive. High flow rate dripperlines (such as Irrigray) apply the graywater directly to the soil zone, and seep into the soil immediately.
What about soap in the fruits and vegetables?
The consensus view is that only tiny amounts could be present and only at a molecular level.
Keep in mind how much the soap/shampoo/conditioner has been diluted by the time it gets to the plant.
Consider how much your body is ingesting through other daily activities (brushing your teeth; direct skin absorption of soap, shampoo, and conditioners; soap residue on plates that you eat off, etc.)
Another consideration is how much pesticide do your store-bought fruit and vegetables contain?
Yuck! Eating vegetables with water I have showered in or washed my clothes in!
Graywater irrigation of fruit and vegetables is, of course, a personal choice. No one is forcing you to grow your fruit and vegetables with graywater. However, on balance it would appear homegrown foodstuffs will have less contaminants than commercially grown produce.
My local regulations prohibit or advise against the use of graywater for vegetables.
Graywater dripperline technology has evolved enormously over the last 6 years in countries such as Australia. The new dripperline technology has only recently arrived in the US, and health department regulations or recommendations take many years to catch up.
We are not recommending that you break the law. We are simply suggesting thinking about why the law was written in the first place.
This chapter is written as general advice, based on our own research and experience. We recommend conducting your own research and/or consult local authorities before deciding what’s best for you.