The Household Power Is Down. Now What?

Installing contractors should prepare homeowners on how to protect their onsite systems during a power outage

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Whenever we conduct workshops on the basics of sewage treatment systems and talk about incorporating pumps, it leads to a discussion of what to tell people to do when the power goes out. If you live in a rural area, you recognize it’s not a question of if the power will go out but when and for how long. Most outages are for a matter of a few hours, but there are times when the power is out for several days to a week or more. It is these longer outages that cause concern for our treatment systems.

Our first reaction is to remind folks that there is another pump to think about when the power goes out, and that’s the well pump. If there is no water coming into the house from the well, the amount of sewage generated will be reduced. Once water is drained from the pressure tank, no more water comes from the well. Any sewage generated will then come from water stored before the outage or carried in from a nearby water source.

One exception to this is when a residence has an automatic generator system that takes over if the power goes off. A note of caution for homeowners is to remember to include the circuits that control the sewage pumps when selecting circuits to receive power from the generator. It is easy to remember the well pump for water, stove, refrigerator, freezer and TV and then forget the sewage pump out in the yard to move sewage from the pump tank to the drainfield.


If they don’t have an automatic generator, homeowners with mounds, at-grade, and pressure distribution systems, or any system that requires a pump must be prepared for the potential multiple-day power outage. Any system with a pump will not be able to transfer wastewater from the septic tank and pump chamber to the disposal field during a power outage.

It is important to minimize use of the septic system to prevent overflow of the septic tank and pump chamber. Toilet flushing should be limited to only solids; any dishwashing should be done in a tub where water can be carried outside and discarded. Showers and baths should be curtailed. The homeowner should monitor the level in the pump tank and, if possible, have a pumper come to remove the contents of pump and septic tanks if they are full.

If the system is an on-demand system, the pump cycle begins whenever the wastewater volume reaches a preset level in the septic tank — usually controlled by floats — and the effluent is pumped into the drainfield. When there is a power outage, effluent is not pumped into the drainfield. The septic and pump tank collect the wastewater throughout the power outage and will release it all at once when the power is restored and the pump starts. Too much water pumped at one time can flood the drainfield, causing surfacing or backups.

To avoid this problem, the homeowner can become a human timer by turning off the circuit to the pump during the outage and when power is restored, run the pump for a typical time period that would deliver a single dose to the drainfield. Turn the pump off and then run it again after a period of four to six hours. In other words, gradually deliver the accumulated effluent to the system over time. The number of cycles required will depend on how much effluent has accumulated in the system.


A pump system with a timer controls the number of times the pump starts and stops. It manages how much effluent (liquid sewage from the septic tank) goes to the drainfield in a 24-hour time period. Timers make sure the drainfield only gets as much effluent as it was designed to handle. The timer system will eventually take care of itself once the power is restored. If the high water alarm sounds when the power is restored, the effluent has backed up into the reserve storage area of the pump tank. It may be necessary to employ the manual override or turn the pump on and off by turning the circuit off to gradually reduce the backup.

Provided by the installer, the homeowner should have an owner’s manual for their onsite wastewater treatment system that explains the components of the system and how they work. Situations such as power outages are why this is important; the manual should explain the amount of dose delivered and the time the pump runs. The manual should be easily accessible in case of emergency or an outage.

If the power has been off for a while, the timer will be behind. To let the timer catch up, the homeowner should continue to conserve water for an additional day or more. This means taking short showers, not doing laundry, and performing other water conserving actions.

These recommendations probably seem to be common sense; but to homeowners unfamiliar with rural areas and individual treatment systems, spending some time explaining how the pumps work and what to do during power outages can save a lot of work and headaches in the future. 


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