Do septic tank additives actually work?

Walk down the cleaning aisle at any hardware store and you will find boxes, pods and bottles promising to “eliminate pumping” or “restore your septic system.” We get asked about them every week. Here is what we tell customers.

How a septic tank works without help

Everything you flush already contains the bacteria a septic tank needs. Those bacteria break down some of the organic waste, but not all of it. The rest settles as sludge, along with inorganic material like sand, hair fibers and food particles that bacteria cannot digest. Grease and oils float as scum. The only way to remove that buildup is to pump it out. No product changes that basic fact.

The three main types of additives

Biological additives (bacteria and enzymes)

These are the most common. They are generally not harmful, but studies and guidance from agencies like the U.S. EPA have not shown that they reduce the need for pumping in a properly working tank. At best they are a small expense with little effect. At worst they give people a false sense of security and they skip pumping.

Chemical additives (degreasers, solvents)

Products that break up grease or “dissolve” sludge can be harmful. They can kill the good bacteria and, more importantly, suspend solids so they wash out of the tank and into the drainfield, where they clog the soil. Washington regulates septic additives and restricts products that contain harmful chemicals for that reason.

Inorganic compounds (acids, alkalis)

Strong acids or bases can damage concrete tanks and baffles and disrupt the bacteria. We do not recommend them.

When people think additives “worked”

Often an additive is poured in right before or after a pump-out, and the system runs better, but the pumping did the work. Other times a slow drain clears up because a clog moved, not because the tank changed. If a problem keeps coming back, something else is wrong.

What actually keeps a septic system healthy

• Pump on schedule. For most homes that means every 3 to 5 years (how often to pump).
• Get regular inspections. King and Snohomish County expect gravity systems to be inspected at least every 3 years and alternative systems more often.
• Watch what goes down the drain. No wipes, grease, paint or medications (what not to flush).
• Spread out water use. Run laundry across the week instead of all on Saturday.
• Clean the effluent filter. Many systems have an outlet filter that should be cleaned regularly.
• Protect the drainfield. No parking, no new trees, keep roof water away.

What about household cleaners?

Normal amounts of household cleaners, laundry detergent and dish soap are fine for a septic system. Problems start with large amounts of bleach, antibacterial products used heavily every day, or pouring chemicals down the drain to clear clogs. Use a plunger or call us instead of drain chemicals.

A better use of the money

Monthly additive subscriptions often cost as much as a real maintenance plan. Our $20/month maintenance plan includes an annual filter cleaning and system check, waived emergency fees, 10% off septic services, and reminders when you are due for pumping. That is maintenance that actually prevents problems.

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