Planting Vegetables Over a Septic Leach Field
By: Julie Day
“Can I plant a vegetable garden on my septic tank leach field?” – Eric
The septic tank leach field is a tempting spot for a vegetable garden – it’s large, flat, and usually sunny. However, it is generally not recommended to plant vegetables in this area, for several reasons:
There is a risk of contamination:
- As septic tank effluent drains out into the lines, it is filtered slowly through the soil, and beneficial soil microbes digest harmful bacteria and viruses. That means that near the lines, there is some amount of contamination, and the extent depends on the type of soil, the rate of absorption, and the quality of the system. While septic systems are designed to prevent disease-causing soil contamination, there’s no easy way to know if your system is functioning properly.
- In addition to bacteria, think about all the household chemicals that go down your drains every day. In general, plants help the environment by absorbing and processing chemicals – which could end up in your vegetables.
- Root crops are more easily contaminated, and their roots can interfere with the drain lines.
- Leafy vegetables can be contaminated by water splashing up from the soil surface.
- Taller or fruiting plants (such as tomatoes, cucumbers) are less likely to be contaminated – problem is, there’s no way to tell what kinds of (or how much) bacteria is on them.
- If you have a water-softener system, it will discharge brine (salt) into the system, which will harm salt-sensitive vegetables such as peppers and beans.
Also, the proper functioning of your septic system can be harmed by:
- Raised beds that interfere with the evaporation of moisture.
- Tilling, digging, and foot traffic, which can damage the septic lines.
- Irrigation, which upsets the careful process of filtering and evaporation.
Instead of vegetables, plant your septic leach field with shallow-rooted, drought-tolerant ornamental plants, grasses, or ground covers. For more information, and plant suggestions check out:
- Planting on your Septic Drain Field (Virginia Tech)
- Planting on Septic Leach Fields (University of Nevada)