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How Do I Know What Size My Septic Tank Is?

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How to find the size of your septic tank

Septic tanks come in all shapes and sizes, and it’s easy to forget — or never learn — the size of the septic tank on your property. Because its size affects how often it should be pumped, however, it’s important to know the size of your septic tank. There’s two ways to do this (but only one way to know for certain).

Rely on current records

This could be paperwork left by the original system installer, the last provider who pumped the tank, or the previous owner.

You can also contact your county’s septic permit offices and request the records on your septic system. These documents can include the location, size, and layout of your septic tank, but are not always accurate.

You can also take a look inside your home for clues. The size of the septic tank you need depends on the number of bedrooms in the home and the home’s square footage. Here’s a table you can use to get some idea of what size your septic tank may be.

# Bedrooms Tank Capacity
1 or 2 750
3 1,000
4 1,250
5 1,500

Hire a septic maintenance provider

Although paperwork and the size of your home can give you an idea of what size septic tank you may have on your property, it may be no more than a guess. Documents can be wrong, and a previous owner may have installed a larger or smaller tank than necessary.

The only way to know for certain the size of your septic tank is to hire a septic maintenance provider to locate, open, and pump the tank. At that time he or she will be able to tell you its exact size and if it’s in good shape or needs maintenance.

Septic tank size affects pumping schedule

Why does it matter if you know the size of your septic tank? Because that affects how often it needs to be pumped to keep operating at its peak.

Generally we recommend pumping your septic tank every 3-5 years — the smaller the tank, the more often it must be pumped. Tanks that go too long without this maintenance are likely to become backed up or fail, requiring expensive repairs or replacement.

We are septic experts

Whether you need help locating, sizing, or pumping your septic tank, Van Delden Wastewater Systems can help. We installed our first septic system in 1937, and specialize in all types of septic systems and Clearstream aerobic systems.

Contact us today for all your septic system needs.


For 86+ years, Van Delden Wastewater Systems has withstood the test of time as the leading Wastewater System company, providing San Antonio, Boerne, and the surrounding Texas Hill Country with services you can count on now and in the future. 

Call us for any of your wastewater systems needs and let our professionals help you with your septic installation and maintenance requirements: 210.698.2000 (San Antonio) or 830.249.4000 (Boerne).