How to Convert a Septic Tank to Storage

Holding tank waste water is commonly field applied in rural farm areas.

Septic tanks can be converted to storage tanks or holding tanks on a temporary or permanent basis. Often, this is done on lake lots where existing drain fields fail to meet treatment standards. Many lake lots are so small they have no room for additional soil treatment systems. In these cases, the local government may allow the existing septic tank to be converted to a storage tank. Licensed pumping companies then remove the waste and deliver it to a municipal sewage treatment plant or it is applied to specially regulated areas or fields.

Things You'll Need

• Shovel
• Excavator
• PVC saw
• Trowel
• Wire brush
• PVC cap
• Mastic sealant
• High water alarm system
• Marker
• Tape measure

Instructions

1. Remove the soil from the outlet of the septic tank using a shovel or excavator. Be careful not to damage the tank as the pressure exerted from an excavator can break a septic tank lid.

2. Remove soil around the outlet pipe until you have room to cut the outlet pipe and remove it from the excavation.

3. Cut the outlet pipe with a PVC saw.

4. Clean the outlet hole in the septic tank of all debris and old sealant with a trowel and wire brush. Allow the concrete to fully dry.

5. Insert a PVC cap into the outlet hole by firmly pushing into the hole.

6. Insert the mastic sealant into the voids between the tank and the cap. Firmly press the sealant into the voids with a trowel.

7. Unplug any existing effluent pumps from the electrical outlet near the tank without disturbing the wiring for the alarm system. The alarm system needs to be intact to announce when tank pumping is necessary.

8. Remove one of the 4 inch inspection caps and set it aside if no high water alarm system exists.

9. Insert the high water system assembly into the inspection pipe. Observe the movement of the pipe from its lowest level to its highest. Be sure the float is free flowing and does not meet any obstructions.

10. Observe the level of the inlet pipe on the alarm assembly. Using a marker, mark this level on the pipe. Measure 4 inches down from this line on the assembly and mark an "x" on the pipe. This "x" will rise above the level of the tank when the tank needs to be pumped.

11. Place the new high water alarm cap onto the inspection pipe by firmly pressing down.

12. Replace the excavated soil with a shovel or excavator.

Tips & Warnings

• Working around septic tanks, septic systems and waste water streams is dangerous. Never enter a septic tank. Wear all appropriate safety equipment and take all appropriate safety precautions.

Resources

• Environmental Protection Agency: A Homeowner's Guide to Septic Systems
• University of Minnesota Extension; Septic System Owner's Guide; Laurie Brown et al; 2008
• North Carolina Cooperative Extension Service: Septic System Owner's Guide