Saving water on a septic system

A septic system is sized for a certain amount of water a day. Go over it and wastewater moves through the tank too fast for solids to settle, then reaches a drainfield that can't absorb it all. Using less water is one of the cheapest ways to make a septic system last.

How much water a household uses

EPA's SepticSmart guidance says the average indoor water use in a typical single-family home is nearly 70 gallons per person per day. Every one of those gallons goes through your septic tank. EPA also points out that a single leaky or running toilet can waste as much as 200 gallons a day, which could nearly double a small household's load without anyone noticing.

Penn State Extension's sizing table shows how systems are designed around flow. In Pennsylvania, a three-bedroom home is designed for an estimated 400 gallons a day and a 900-gallon minimum tank. A four-bedroom home is designed for 500 gallons a day and a 1,250-gallon tank. Other states use different numbers, but the principle is the same. A system has a daily budget.

Fix leaks first

• Toilets: put a few drops of food coloring in the tank and wait 15 minutes without flushing. Color in the bowl means the flapper leaks.
• Faucets and showerheads: a steady drip adds up over a day.
• Well pump running when nothing is on: on a private well, this can reveal a hidden leak. The water also ends up in the septic system if the leak is inside.

Use efficient fixtures

EPA's SepticSmart advice recommends high-efficiency toilets, faucet aerators, and high-efficiency showerheads, all of which reduce the volume of water reaching the system. When you replace a toilet, washing machine, or dishwasher, look for the WaterSense or ENERGY STAR label.

Spread out the laundry

EPA specifically advises spreading laundry through the week instead of doing it all on one day. Several loads in a row can send hundreds of gallons to the tank in a few hours. Run full loads, and choose the right load size setting.

Keep outside water out

Rainwater isn't wastewater, but it can still overload a system. Point roof drains and sump pump discharges away from the drainfield. Never drain a hot tub, pool, or large aquarium into the septic system. Drain it elsewhere, following local rules.

Garbage disposals

A disposal doesn't use much water, but it sends a lot of food solids to the tank, which fills faster and needs pumping more often. If you have one, use it sparingly, and scrape plates into the trash or compost. See what not to flush.

What it buys you

Less water means wastewater stays in the tank longer, more solids settle, and the drainfield gets a steadier, lighter load it can absorb. That's less risk of backups, longer drainfield life, and fewer emergency calls. Pair it with regular pumping. Our pumping calculator gives a starting schedule.