How to Treat Cesspools with Caustic Soda

A cesspool is a wastewater disposal system that combines a septic treatment tank and absorption system into a single component. Overtime sludge and grease builds up on the walls, and failure to remove the sludge and grease will cause the cesspool to fill up faster. Luckily you can use caustic soda to help break down the grease that builds up on the wall. With the right directions you can quickly treat the cesspool with caustic soda.

Things You'll Need

  • Caustic soda

  • Safety glasses

  • Rubber gloves

  • Long-sleeve shirt

  • Pants

  • Garden shovel

Step 1

Do not attempt to pump the cesspool yourself. Call a septic tank contractor and have them pump the cesspool clean. Only a licensed septic tank contractor can legally pump a cesspool. The cesspool must be cleaned before adding caustic soda.

Step 2

Identify the size of the cesspool in gallons. Either the cover of the cesspool will list the size in gallons or it will be listed in the official building plans. If you cannot locate the size of the cesspool, ask the septic tank contractor to give you the size in gallons after they pump the cesspool. The septic tank contractor can tell the size of the cesspool from the amount of liquids pumped out of it.

Step 3

Wear a long-sleeve shirt and pants. Also wear safety glasses and rubber gloves. Cover as much of your skin as possible to ensure you do not get caustic soda on you.

Step 4

Add 100 pounds of caustic soda for every 2,000 gallons in capacity of the cesspool. Spread the caustic soda evenly over the cesspool using the garden shovel to spread it. Make sure caustic soda lands on the walls of the cesspool and the floor.


You can buy caustic soda at most plumbing supply stores. Major hardware stores also carry caustic soda, but in small quantities.


If your cesspool has failed and cannot be pumped, you must install a new septic tank system with drain field to replace the existing cesspool. If you get caustic soda on your skin immediately flush the area with running water and seek medical attention.

References & Resources