Used nutrient water from your Flex Farm, Flex Acre, Flex Micro or Flex Connect can go down an indoor sink, floor drain or mop sink, or you can reuse it to water lawns, trees and garden beds. It is dilute plant fertilizer: about as strong as houseplant plant food and about as acidic as rain. The one rule: keep it out of storm drains, ditches, streams and ponds.
Where It Can Go
| Yes | No |
|---|
| An indoor sink, utility or mop sink, or floor drain that goes to the sewer | Storm drains: street grates, parking lot drains, gutters and downspouts |
| Lawns, trees, shrubs, flower beds and garden beds | Ditches, streams, ponds and lakes, or near a well |
| A compost pile | Full-strength pH Down or dry nutrients poured straight down a drain |
Option 1: An Indoor Drain
Drain your system into a sink, mop sink or floor drain, as the draining steps in How to Refresh the Water in Your Flex Farm and Refreshing your Flex Acre Water show. Indoor drains go to the sanitary sewer and on to a wastewater treatment plant, which is built to remove nitrogen and phosphorus, the same nutrients your plants use.
- Run cold tap water while you drain. It dilutes the water further on its way out.
- Use a drain inside the building. Floor drains in garages, loading docks and some basements can connect to the storm sewer. If you are not sure where a drain goes, ask your facilities team.
- Water from cleaning your system with 3% hydrogen peroxide goes down an indoor drain too, not onto plants.
Option 2: Reuse It Outdoors
Nutrient A and Nutrient B are made of the same ingredients as ordinary garden fertilizer, so old nutrient water is a free, gentle feeding for other plants. Good places to use it:
- Lawns and sports fields
- Trees, shrubs and hedges
- Flower beds, planters and school or community garden beds. Water the soil around the plants.
- A compost pile that needs moisture
- Houseplants and seedlings, mixed half and half with plain water
To keep it gentle on the ground around you:
- Spread it over a wide area instead of dumping it in one spot, so the soil can soak it up.
- Skip frozen or soaked ground, and skip days when heavy rain is coming, so it doesn't run off.
- Stay well back from storm drains, ditches, streams, ponds and wells.
- Send it to an indoor drain instead if your system had root rot or another plant disease, or if anything other than nutrients and pH Down is in the water.
- Some places limit phosphorus fertilizer on lawns. Minnesota is one. There, use it on garden beds, trees and flowers instead of grass.
If your building is on a septic system rather than city sewer, reusing the water outdoors is the simplest choice.
What's in Used Nutrient Water
- The ingredients. Nutrient A holds potassium nitrate, potassium phosphate, potassium sulfate, magnesium sulfate (Epsom salt) and trace minerals such as iron, zinc and boron. Nutrient B is calcium nitrate. pH Down is a phosphoric acid solution. All of them are listed on the Safety Data Sheets for Fork Farms Growing Supplies.
- How strong it is. Your nutrients sit at your plain-water reading plus 700 PPM, as set in How to Check and Adjust Flex Farm Nutrients and pH. That is about the strength of all-purpose plant food mixed at the houseplant rate on its label, and weaker than the rate the same label gives for outdoor plants.
- How acidic it is. Your water is kept between pH 5.5 and 6.5. Normal rain is about pH 5.6.
- How much there is. A Flex Farm runs on about 25 gallons, and a Flex Acre about 80. For how often to change it, see How to Refresh the Water in Your Flex Farm.
One Flex Farm water change carries less nitrogen and phosphorus than an average family of four sends down its drains in a single day.* A full Flex Acre water change carries less than two such families do.
The Rules That Apply
- Your local sewer utility sets the rules for drains. Under the EPA's National Pretreatment Program, the federal limits are that nothing that goes down a drain may disrupt the treatment plant, and nothing may be more acidic than pH 5.0. Used nutrient water is well inside both limits. Some cities set a stricter pH limit, such as 5.5 or 6.0; running tap water while you drain helps you meet it.
- Federal facilities follow the same local rules. Under section 313 of the Clean Water Act, federal buildings such as federal prisons, military bases and VA hospitals follow the same local sewer rules as everyone else.
- It is not hazardous waste. Under federal waste rules, a liquid counts as corrosive hazardous waste only at pH 2 or lower. Used nutrient water is far above that.
- Your facility's own policy comes first. Many schools, hospitals and correctional facilities have their own rules for what goes down a drain. This article and the Safety Data Sheets are what your safety or facilities team needs to review it.
Want written approval? Send your city or county wastewater utility the Safety Data Sheets and a link to this article, and ask whether your local sewer rules allow it. Search for your city's name and "wastewater pretreatment" to find the right office.
Leftover Products and Empty Containers
- Dry Nutrient A and Nutrient B keep well. Use them up, or give unwanted bags to a garden as fertilizer. Don't pour dry nutrients down a drain.
- pH Down: use it up in your tank, and never pour it straight down a drain or onto soil. For a bottle you no longer want, use your facility's chemical waste process or a household hazardous waste drop-off. Before handling pH Down, read its Safety Data Sheet.
- Empty bottles and bags: rinse three times with water, pour the rinse water into your tank, then recycle or throw away the container under your local rules.
- Spills: sweep up dry nutrients and reuse them. For a pH Down spill, follow its Safety Data Sheet.
Common Questions
Can I pour hydroponic nutrient water down the sink?
Yes. Used nutrient water from Fork Farms systems can go down an indoor sink, mop sink or floor drain that goes to the sewer. Run cold tap water while it drains. Never pour it into a storm drain.
Can I use old nutrient water on my lawn or garden?
Yes. It is dilute fertilizer, so it is good for lawns, trees, shrubs, flower beds and garden beds. Spread it out, skip frozen or soaked ground, and keep it away from storm drains, ditches, streams, ponds and wells.
Is it safe to water vegetables with it?
Yes. It is the same fertilizer that feeds the crops in your Fork Farms system. Water the soil, not the leaves, and wash produce before eating as usual. Don't reuse water from a system that had root rot or another plant disease.
The Safety Data Sheet says to dispose of the product "in accordance with federal, state and local regulations." Does that mean it can't go down the drain?
No. That standard wording is about the concentrated product in bulk, not the dilute water in your tank. OSHA does not enforce the ecology and disposal sections of a Safety Data Sheet because other agencies handle those topics. For a drain, the rules that apply are your local sewer utility's, and used nutrient water fits within them.
Do I need permission from my city to drain it?
Usually not for household-sized amounts like these. If your facility wants written approval, send your local wastewater utility the Safety Data Sheets and a link to this article.
Our building is on a septic system. What should we do?
Reuse the water outdoors on lawns, trees or garden beds, following the steps above.
How We Worked Out the Comparison
* To stay conservative, we used the strongest water you would ever drain: 30 gallons at the top of the nutrient range. From our dosing (1 tablespoon each of Nutrient A and Nutrient B raises a Flex Farm by about 230 PPM) and the formulas on the Safety Data Sheets (Nutrient A 4-14-34; Nutrient B calcium nitrate), one Flex Farm water change holds at most about 17 grams of nitrogen and 6 grams of phosphorus. The EPA's Onsite Wastewater Treatment Systems Manual (Table 3-8) puts average household wastewater at 11.2 grams of nitrogen and 2.7 grams of phosphorus per person per day: about 45 grams and 11 grams for a family of four. A Flex Acre holds about three times the water of a Flex Farm.
Sources
Questions? Contact us at 877-886-7736 or support@forkfarms.com.
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