Sewer backup in a multi-tenant building: what first?

1. 1Get people out of the affected area. Sewage carries bacteria, and the space may hold sewer gas. OSHA notes that hydrogen sulfide, a gas found in sewers, smells like rotten eggs at low levels, causes effects from headaches to unconsciousness at higher levels, and can stop being noticeable to the nose. If anyone feels dizzy or ill, move them outside and call 911.
2. 2Ask tenants to stop using water. Toilets, sinks, dishwashers and floor drains all feed the same line. Every flush adds to the overflow, so a building-wide notice to stop using plumbing fixtures until a plumber clears the line limits the damage. A short announcement or a group text is enough.
3. 3Find the lowest drains. Sewage comes out at the lowest point in the system first, so the ground floor, basement drains and floor sinks are usually where it shows. Where it appears helps the plumber judge where the blockage is.
4. 4Call a commercial plumber. Give the address, which fixtures are backing up, which tenants are affected, and how to get in after hours. Our after-hours commercial plumbing checklist lists what to have ready.
5. 5Check whether the street is involved. If sewage is coming out of a manhole in the street or neighboring buildings are also backed up, report it to the city. In Phoenix, Water Services runs a 24/7 emergency line at 602-261-8000 for water and sewer emergencies such as main breaks and overflows.
6. 6Photograph and record. Take photos and video of the source and the damage, and note the times, before anything is cleaned or moved. You will need them for insurance and for any dispute over who pays.

### Why treat the smell as a warning sign?

It is tempting to judge a backup by how strong the odor is. OSHA's hydrogen sulfide page warns against that. It says the gas smells like rotten eggs at low levels, but that a person can lose the ability to smell it after a while, or quickly at high concentrations. So a room that seems to smell less may not be safer. Keep people out of low or closed-in areas near the backup, such as basements, pump rooms and utility closets, until the plumber has cleared the line and the space has been aired out. If anyone reports a headache, dizziness or eye irritation, get them into fresh air and call for medical help.

A plumber usually answers this with a camera and a cleanout. If the blockage is in the lateral that runs from the building to the city's main, it is the owner's line. The City of Phoenix says property owners maintain the sewer lines that run through their property and connect to the city's mains. If the blockage is out in the main, the city handles it. Our page on who is responsible for the sewer line in Phoenix explains the split. A backup that hits several tenants at once, or the lowest units first, points toward the shared building line, and main line versus branch clog signs shows how to tell.

Sewage is a health hazard. The CDC's guidance for anyone cleaning up sewage is to wear rubber boots, goggles and gloves, and to cover any cuts with a waterproof bandage. Have a professional cleanup or restoration crew handle anything beyond a small spill. Do not let tenants or staff mop up sewage without protective gear. Porous materials that soaked up sewage, such as carpet and drywall, often have to be removed, and a restoration contractor can advise on what to save. If food is stored in the space, ask the health authority before selling anything that may have been exposed.

### What about food-service tenants?

Treat a sewage backup in a restaurant or café as a reason to stop food service until the problem is fixed and the county agrees. Maricopa County's Environmental Health Code, Chapter VIII Section 2, lists sewage backup among the imminent health hazards, alongside fire, flood and a water or electrical outage. The sentence we found sits in the rules for a change of ownership, where a new owner must agree to "immediately cease operations" if one of those hazards occurs. It shows how the county views a backup, but it is not a standalone closure order for every tenant. So tell food-service tenants right away, and suggest they call the county's environmental health office before they reopen. Do not promise a reopening date. That call belongs to the health authority, not the landlord or the plumber.

### What should the tenant notice say?

A short written notice does more good than a long one. Cover these points:

1. 1What happened and when it was found.
2. 2Which fixtures and areas are affected, and which to avoid.
3. 3That tenants should stop using toilets, sinks and floor drains until the plumber says the line is clear.
4. 4Who to call with questions, and how you will update them.
5. 5A reminder to photograph any damage to their own goods and to notify their own insurer.

Keep the tone factual. The notice should state what you know and leave out guesses about the cause or who is at fault.

### How do you keep the record straight?

Start a simple log the moment you learn of the problem. Note the time of each call, who reported the backup, when the plumber arrived, what was found and what was done. Keep the plumber's invoice and any camera video. If the backup was in the shared building line, the log shows the property was on it quickly. If it was in the city's main, the log shows when you reported it. Phoenix Water Services keeps a 24/7 line for water and sewer emergencies, so a call to it is worth noting in the record.

### What happens after the line is cleared?

Clearing the stoppage ends the emergency but not the job. Ask the plumber where the blockage was, what caused it, and whether a camera pass is warranted. Repeat backups point to a defect in the line or to something being flushed or poured down it, and a camera inspection can find it. Then do the cleanup properly. The CDC's advice to wear rubber boots, goggles and gloves applies to everyone who touches affected areas, and porous materials that soaked up sewage should be assessed by a restoration contractor. When the area is dry and clean, tell tenants in writing that it is safe to return.

For a longer-term plan, see how a commercial preventive maintenance plan cuts down on backups.

• Notify affected tenants in writing. Say what happened, when, and what you are doing. Written notices help later if a tenant claims lost business.
• Read the lease. Who pays for the plumbing repair, and who pays for a tenant's damaged goods, comes down to the lease and to the cause. Our page on tenant versus landlord plumbing responsibilities covers the usual split.
• Call your insurance carrier. Sewer backup coverage is often a separate endorsement, so check the policy early. Our page on whether insurance covers a sewer backup explains why the exclusion is common.
• Fix the cause, not just the symptom. A blockage that returns points to a line problem or heavy grease, which a camera inspection can find. Restaurants in the building should see the commercial kitchen drain page.

Tenants deciding whether to stay open should also read what the rules say about a business with restrooms out of service.

HQ offers 24/7 emergency service, is licensed and insured, and gives upfront pricing and free estimates.

HQ offers 24/7 emergency service, is licensed and insured, and gives upfront pricing and free estimates.

A broken water main is a different emergency; see what a property manager does when a main water line breaks.