What is a Cesspool vs a Septic System in Hawaii?

Many of our buyer and seller clients have asked me to help explain what the differences are between two of the most common waste management systems in Hawaii, which are cesspools and septic systems. Simply put, I hate cesspools and they have cost me a lot of money in my real estate career and as the owner of various Hawaii properties throughout the last 30 years.

The Benefits of a Septic System

A septic system is multipart, with a tank that usually has a capacity between 1,000 to 1,500 gallons, a baffle and distribution box, and then a drain field that has manifold for liquid distribution. The septic system is aerobic, and breaks down the waste water quickly and percolates it back into the water table.

septic system

A Septic System

Cesspools do a terrible job of processing the water in general, but in high drainage areas just pass the water into the water table untreated and thus commonly create pollution in ground water sources.

Since 1992, it has been illegal to construct a home in Maui using a cesspool. Septic systems were required starting in 1992. Most rural areas in Hawaii are not served by sewer and therefore either have a cesspool or septic system.

How to Find a Cesspool in Your Yard

A cesspool is just a big hole, generally with no lining at all from 12 to 20 feet deep, with a concrete cap on top with a pumping port. The system is anaerobic, by nature, and waste decomposes very slowly. Some basics, first of all make sure the house was built pre-1993. If it was, it probably does have a cesspool and not a septic system.

Cesspools, by code, have to be located at least 10 feet from the wall of the house. If the house is post and pier, you can look under the house and see the direction that the big 3 or 4-inch final drain goes. The cesspool is on that side of the house.

If you have a slab house, it is tougher. Look for a clean out around the outside perimeter of the house that a plumber might use to clean out the line. Usually, that main clean out goes to the cesspool.

Finally, ask the present owner or tenant if they have seen a brown circle in the yard when it was not raining very much. The soil on top of a cesspool usually dries out quicker than the surrounding yard. If they have a general idea of where the cesspool is, take a hollow tile block (a big heavy one), lift it high, and drop it. If you are over the cesspool, the ground vibrates a lot. If you are over dirt, it just goes “thud.” Generally, the pumping port, or “cork” as I call it, is in the center of the concrete.

Generally, plumbers can find cesspools like this, or the pumping companies can do it. I do it a lot of the time when I take the listings on rural houses that I sell.

Diagnosing and Trouble-Shooting Cesspools

Once you have found the cesspool, find the cork in the cap, pull the cap, and see how high the water is. If it is within 4 feet of the top, you have a problem. You can treat a high cesspool with Sodium Hydroxide that you can buy in barrels at Brewer Environmental in Wailuku, or at other fertilizer stores in Hawaii, and the water generally will drop, but you really have to stay on top of them.

Remember, if you have a house and cottage hooked up to a single cesspool, the owner is in violation of Federal “large capacity cesspool” laws. This is a very expensive problem to deal with.

Once you have to pump a cesspool more than 2 times a year, it is considered a failed cesspool by the State Department of Health in Hawaii and they will want you to replace the system with a modern septic system. On very small lots and ones that are difficult to navigate with large equipment, this can be difficult, if not impossible.

In summary, if you are purchasing a home in Hawaii, built pre-1993, that does not receive a sewer bill, you better be very careful. You could literally have a $15,000 bill two weeks after closing to replace a failed cesspool with a new septic system. I know. I have been there.

Aloha from the guy who has seen just about it all in Hawaii real estate,

Tracy Stice, R(B)

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