Blocked Drain in an Office Out of Hours: What Building Managers Should Do

If toilets or floor drains are backing up in an office after hours, stop use of the affected facilities, find out where the building's inspection chambers are and who holds the keys to them, and decide whether the building needs to be clear by opening time. If it does, an overnight clearance is usually the cheapest outcome once lost working hours are counted. The rest of this guide explains how to make that decision quickly and what the engineer will need from you.

Why office blockages are different from house blockages

An office drain carries far more toilet use per day than a house, often through longer horizontal runs, and access is controlled by someone other than the person reporting the problem. Most of the delay on commercial call-outs is access, not clearance.

Typical causes are the same as anywhere else, just in larger quantities: wipes, paper towels and sanitary items in WCs, and fat and food waste from a tea point or staff kitchen that has been poured down a sink for years. In older central London buildings, drains often run under the ground floor or through a basement before reaching the sewer, and many basements rely on a pumped sewage system. A failed pump or a tripped float switch looks exactly like a blocked drain from upstairs.

First steps when the call comes in

Close the affected toilets, put signs up, and ask the security desk or cleaners to stop running water in that part of the building. Then gather the three things an engineer will ask for before they can start work.

• Access. Who can open the building, the plant room, the bin store or the car park where the manholes are? If a concierge or security guard is on site, tell them a drainage engineer is coming and where they will need to go.
• Location of chambers. Drainage drawings, an O&M manual or a previous survey report will save time. If nobody has one, knowing which door the chamber covers are near is still useful.
• Pumping station details. If there is a basement sewage pump, check the control panel for alarm lights and whether the pump has power. Note the make and any contract details on the panel.

If sewage is escaping into occupied areas, a kitchen, a server room or a lift pit, treat it as an emergency regardless of the hour.

Clear it tonight or wait until morning?

If the building opens in the morning and the blockage affects the only toilets on a floor, clear it overnight. If there are other working facilities and nothing is escaping, a morning clearance at the standard rate is often fine.

Employers must provide sufficient toilets and washing facilities for the people at work under the Workplace (Health, Safety and Welfare) Regulations 1992. A floor full of staff with no working toilets is not a situation you can run for long, and sending people home costs more than any time-band difference. Overnight work also has a practical advantage in a busy office: the engineer can lift chambers in reception, the car park or the corridor without anyone walking past, and the jetting unit can be parked where it needs to be before daytime loading restrictions begin.

Our rates are set by the clock, not the day of the week. A job attended between 7am and 5pm is the standard rate, 5pm to midnight is the evening rate, and midnight to 7am is the night rate. Current figures are on the pricing page, and the job price is agreed on the phone before anyone is dispatched.

Who is responsible: landlord, tenant or managing agent?

It depends on the lease. In a whole building let on a full repairing lease, the tenant usually pays. In a multi-let building, the landlord or managing agent is usually responsible for common drains and recovers the cost through the service charge.

The practical rule is to report it to whoever manages the building first, because they may have a drainage contractor they are obliged to use, and because a blockage in a shared stack or basement run will affect other tenants too. If you cannot reach them and sewage is escaping, arrange the clearance and keep the engineer's report, which records where the blockage was and what caused it. That report is what settles the argument about whose cost it is afterwards. For blockages below the public highway or in a sewer shared with neighbouring buildings, the water company is responsible.

What happens on the night

The engineer finds the chamber immediately downstream of the blockage, relieves the pressure, and clears the run from there with jetting or rods. A camera check then confirms the drain is flowing and shows what caused it.

For long horizontal runs and fat build-up from staff kitchens, high-pressure drain jetting is usually the right method, because it scours the full bore of the pipe rather than just punching through. Where the blockage is inside a soil stack on an upper floor, access is often through a rodding eye behind a WC panel or in a riser cupboard, so knowing where those are saves time. If the camera shows a structural fault, the repair is quoted separately and can be booked for a quieter time.

Stopping it becoming a regular call-out

If the same office blocks more than twice a year, the cause is usually fat from a kitchen, wipes being flushed, or a pipe with a sag or a displaced joint. Each has a different fix, and a camera survey tells you which one you are dealing with.

Signs in the toilets asking people not to flush wipes or sanitary items, proper sanitary bins in every cubicle, and a strainer in the tea point sink cost very little. For buildings with a basement pumping station or a history of blockages, a planned maintenance visit is cheaper than repeated emergency call-outs, and our commercial drainage contracts are set up for that.