University of Maryland Extension

Hiring a Good Septic System Inspector

You want to hire an inspector that says he or she will locate and unearth each and every component of your septic system and inspect it. You do NOT want an inspector that comes out and merely walks around, or, simply flushes a dye pack down the toilet. This is not an inspection, and it will not tell you the system is functioning properly or what needs attention.

 While doing the inspection, a good inspector will run water into the tank from the house, like through a bathtub faucet. The inspector should look into each opening of the septic tank, making sure the baffles are OK, the tank is not showing signs of backup and failure, and measure the depth of the scum layer and sludge layer.

Sludge Tools

Traditional concrete septic tank with built-in concrete baffle. The pole is a hollow tube used to measure the depth of the sludge at the bottom of the tank.


A good inspector will also locate and open up the distribution box, and inspect it to ensure each tile line is receiving the same amount of effluent, and all are draining properly. This inspection will also show if solids have been allowed to escape the tank. (An early warning sign of possible failure down the road.) Looking into the distribution box is probably the most telling part of the inspection process.

Distribution Box

Wastewater from the septic tank is entering on the left. The drainfield has three lines. Note the distribution box is barely filled with wastewater, and all the lines are getting the same amount. That means the drainfield is draining properly.


Lastly, a good inspector will dig down into the drain lines and make sure they look good.

Inspector digging down into drain lines


This type of thorough inspection will cost you more money than the bogus walk about inspections, but it will be money well spent. If you are purchasing a home on a septic system, this thorough inspection will alert you to possible huge expenses that could be incurred if the system is failing. Better to negotiate this up front!

 So be sure to interview inspectors on the phone to find out if they will locate and inspect each component. If you find several who promise to do those things, then it's a matter of price, and timing. BE PRESENT when the inspection is done!

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