What does a lift station alarm mean and what should I do?

1. 1Cut water use. Tell staff and tenants to stop running dishwashers, washing machines, mop sinks and anything else that sends a lot of water down the drain. Environment One, a grinder pump maker, puts it simply: "discontinue water use to avoid causing a backup or overflow."
2. 2Don't silence it and carry on. Silencing the horn is fine so people can think, but the same maker warns: "Never silence the alarm and continue using water if your pump is not working; you will cause a backup or overflow and possibly damage the pump."
3. 3Check for a power outage. If the building or the block just lost power, the pumps stopped with it. Environment One notes that after a power loss the level can rise above the alarm point, and the pump needs several minutes to bring it back down once power returns. If the alarm clears on its own after power comes back, log it and keep an eye on it.
4. 4Call the 24-hour number. A lift station permitted under Arizona's sewage collection system rule must carry at least one warning sign with the owner or operator's 24-hour emergency phone number. Call that number, or your service company, and tell them whether the light is on steady or cycling on and off.
5. 5Keep everyone out of the well. Don't open the hatch to look, and never climb in. See the safety section below.

If sewage is already backing up inside or surfacing on the ground, keep people away from it and treat it as an emergency call. The station's operation and maintenance manual should list the spill response steps and who to notify.

Arizona's 4.01 rule for sewage collection systems (R18-9-E301) requires that "excessively high or low levels of sewage in the wet well trigger an audible or visible alarm at the wet well site and at the system control center." So a permitted site station has two kinds of alarm:

• High level. The wet well is filling past the pumps' normal on and off points. This is the urgent one, because the next stop is a backup.
• Low level. The level has dropped below where it should. It won't flood anything, but it means the level controls aren't doing their job, and the operator should check it.

Smaller pumps inside a building, the kind that lift sewage from a basement restroom, often have a high-water alarm too. The plumbing code's sump section doesn't itself require one, so on those systems the alarm comes from the pump maker or the designer. It means the same thing: the pit is filling faster than it's emptying.

### Steady, flashing or on and off?

Pay attention to how the alarm behaves, because it tells the service company where to start. Environment One's guidance is direct: "If the alarm turns on and off repeatedly or turns on and stays on, call an authorized service center for service." An alarm that comes on once during a big surge and clears in a few minutes may be the pumps catching up. One that stays on, or keeps cycling, means a pump, a float or the controls need a look.

When you call, have this ready:

• Which light or horn is on, and whether it's steady or cycling.
• When it started, and anything unusual right before it (a power blip, a big drain-down, a storm).
• Whether any drains in the building are slow or backing up.
• Whether you can hear a pump running at the station.

That short report can save a trip back for the right part.

The causes are a short list. The U.S. EPA's guidance on lift station maintenance names the usual risks behind sewer overflows: blockages, structural, mechanical or electrical failures, not enough capacity, too much stormwater getting in, vandalism and flushable wipes. At a single station, that usually looks like one of these:

• A pump failed or tripped. A burned-out motor, a tripped overload or a failed control. Most stations have two pumps so one can carry the load, but a station running on its backup has lost its safety margin.
• Rags, wipes or grease jammed a pump. EPA's guidelines say a monthly amp reading outside the maker's specs "is an indication that rags or debris could be lodged in the impeller."
• A stuck float. EPA says "the buildup of grease prevents floats from working properly," which is why it recommends cleaning and inspecting floats four times a year.
• A power outage with no standby power, or a generator that didn't start.
• A surge of water. Environment One notes an alarm can come from a large amount of water going in at once, such as draining a big tub. On a commercial site, think of a pool drain-down, a burst water line or a building flush after a shutdown.

A short alarm after a surge that clears by itself is one thing. An alarm that stays on, or keeps coming back, means something is wrong.

A wet well is a confined space. OSHA defines one as a space big enough to enter that has limited ways in or out and isn't designed for people to stay in, and it names vaults and pits as examples. A space that can hold a hazardous atmosphere is a permit-required confined space, with training, testing and rescue rules that apply to anyone who goes in. Arizona's 4.01 rule tells lift station operators to follow "all applicable state and federal confined space entry requirements."

The main hazard is hydrogen sulfide, the sewer gas that smells like rotten eggs. OSHA says it is "heavier than air," builds up in "manholes, sewers, and underground vaults," and that after a while "you can no longer smell it to warn you it's there." At 700 to 1,000 parts per million, OSHA lists "rapid unconsciousness" within one or two breaths. So a quick look inside with your head over the hatch is not a harmless check. Leave it to the operator.

Get the cause in writing. Ask the service company what they found, what they replaced and whether both pumps are working. Keep a log of alarm dates and causes, because a pattern tells you more than any single call. Keep it with the rest of your commercial plumbing preventive maintenance plan records.

Then look at prevention. EPA recommends inspecting the light and alarm systems weekly, since "an alarm system in working order can alert you to problems immediately." Our page on how often to service a commercial lift station lays out the full schedule, and sewage lift station basics explains how the parts work together. If the station belongs to your property, who owns and maintains a private lift station covers what the owner is on the hook for.

If the alarm came with slow or backed-up drains inside the building, the problem may be in the lines, not the station. HQ Plumbing and Air answers 24/7 and can camera and clear commercial drain and sewer lines, with the price given up front before work starts.