The usual answer is every three to five years. That is a good starting point and a poor stopping point. How often your own tank needs pumping depends on who lives in the house, how much water they use, what goes down the drain and how big the tank is. This guide walks through each of those, plus the measurements a provider uses to decide, so you can plan a pump-out instead of reacting to one.
What a pump-out is actually removing
A conventional septic system has two main parts, according to the US Environmental Protection Agency: a buried, watertight tank and a drainfield. Wastewater from the house flows into the tank. Heavy solids settle to the bottom as sludge. Grease and lighter solids float to the top as scum. The liquid in the middle flows out to the drainfield, where soil microbes finish the treatment.
Only the liquid is supposed to leave the tank. Sludge and scum stay behind, and they build up for as long as the tank is in use. When the layers get too thick, there is less room for the liquid to sit and settle, and solids can pass through to the drainfield. A drainfield that has taken on solids can clog, and that is the repair that costs real money. Pumping empties the tank before that happens.
The four things that change your schedule
The EPA lists four factors that affect how often a household tank needs pumping:
- Household size. More people, more wastewater.
- Total wastewater generated. Long showers, big laundry days and leaky fixtures all add up. The EPA says indoor use can reach about 70 gallons per person per day, and a single running toilet can add up to 200 gallons a day.
- Volume of solids in the wastewater. A garbage disposal sends more solids to the tank. One cost guide lists heavy solids, such as those from a disposal, as a reason to pump more often.
- Septic tank size. A bigger tank takes longer to fill.
The EPA does not give one schedule for every house. Two cost guides both say larger households need pumping sooner than the three to five year norm, so a full house with a small tank is the case most likely to need the short end or less.
How a provider decides
The EPA gives three thresholds for when a tank should be pumped:
- the bottom of the scum layer is within six inches of the bottom of the tank outlet,
- the top of the sludge layer is within 12 inches of the outlet, or
- sludge and scum together fill more than 25 percent of the liquid depth.
You cannot check these yourself, and you should not try. Tanks can contain dangerous gases, and nobody should open or enter one. Do not lean over or climb into an open tank, even for a quick check. A trained provider can measure the layers when the lid is off. That is the reason a pump-out visit is also a good time to ask what they found, how thick the layers were and when they suggest the next visit.
If you have a system with pumps, float switches or other moving parts, the EPA recommends inspecting it about once a year, because those parts can fail between pump-outs.
What Lawton homeowners might think about
Soil and the drainfield. Soils in Comanche County vary, and a general description cannot tell you what is under your yard. For reference, the USDA's official description of the Lawton soil series, whose type location is in Comanche County, calls it a well drained soil with moderately slow permeability and a clay content of 35 to 40 percent in its main section. That series is one soil among many in the area, so do not assume it applies to your lot. A permit file, or a provider who has serviced systems nearby, may tell you more about your site.
Weather. Lawton has a humid subtropical climate, with annual precipitation in the high 20s to low 30s of inches depending on the source, and very hot summers. When heavy storms come, they can saturate the ground over a drainfield. One cost guide lists groundwater saturation from rain or flooding among the things that can make a system need attention more often. If your yard stays soggy over the drainfield, mention it to a provider.
Household changes. A new baby, a relative moving in, a remodel that adds a bathroom, or switching to a garbage disposal all change the load on the tank. If your household has changed since the last pump-out, the old schedule may no longer fit. Ask a provider to look.
Military moves. Lawton is home to Fort Sill, the city's largest employer according to the Wikipedia article on the city. Anyone who rents or buys a home that is outside the sewer lines may be taking on a tank with no records. Ask the seller or landlord for the pumping history, and if there is none, treat the tank as due and ask a provider to check.
Ways to stretch the time between pumpings
The EPA says a septic system is not a trash can. Only human waste and toilet paper belong in the toilet. It lists cooking grease and oil, wipes labeled as wet or baby wipes, feminine hygiene products, diapers, cat litter, paper towels, pharmaceuticals and household chemicals such as paint thinner and pesticides as things to keep out of the system.
A few other habits from the same page:
- Spread laundry across the week instead of doing it all in one day. A heavy day can flood the drainfield.
- Replace old toilets with high-efficiency models that use 1.6 gallons or less per flush, and use faucet aerators and efficient showerheads.
- Fix leaking toilets and faucets.
- Do not park or drive on the drainfield, and do not plant trees or shrubs over it.
- Keep roof drains and sump pump discharge away from the drainfield.
One cost guide says microorganism additives should not be used to avoid routine pumping. Do not count on a product to replace pumping. If a product claims to, ask a provider before using it.
Keep a record
Write down the date of each pump-out, the size of the tank, who did it and anything they noticed. A record lets the next provider, or the next buyer of your house, see the pattern. If you move into a house with a tank and no records, the safest assumption is that it needs a check.
Request a quote
If you do not know when your tank was last pumped, or you think it may be due, request a quote through this site. An independent provider in the Lawton area can look at the tank and tell you what they see. There is no charge to ask and no commitment to hire.
Common questions
Is every three to five years right for every house?
It is a typical range, not a rule for your house. Household size, water use, solids and tank size all move it. A provider who measures the layers in your tank can give a better answer.
Can I just wait until something goes wrong?
That is the risky way to do it. A backup into the house is unpleasant, and solids that reach the drainfield can damage it. Regular pumping is cheaper than repairing a drainfield.
Do I need to pump if my tank was pumped when I bought the house?
Ask when. If you do not know the date of the last pump-out, a provider can check the layers and tell you whether it is due.
Is a bigger household a reason to pump more often?
Yes. More people means more wastewater and more solids. The EPA lists household size as one of the main factors.