Short answer: manufacturers' instructions quote BS EN 12056-4 for how often a wastewater lifting station inside a building is serviced. Wilo's instructions give every 3 months for commercial premises, every 6 months for blocks of flats and once a year for a single house. A service checks connections, the non-return valve, the level sensor, the controller and alarm, and the pump, then ends with a test run. Do not go into a wet well, pit or sewer unless it is essential: HSE treats these as confined spaces.
When a building needs a pumping station
In England, Approved Document H (2015 edition) says a pumping installation will be needed "where gravity drainage is impracticable, or protection against flooding due to surcharge in downstream sewers is required" (para 2.36). It goes on:
- Package pumping installations inside buildings should conform to BS EN 12050, and pumping installations inside buildings should be designed to BS EN 12056-4 (para 2.37).
- Guidance on pumping installations outside buildings is in BS EN 752-6 (para 2.38).
- Where foul water is pumped, the receiving chamber "should be sized to contain 24-hour inflow to allow for disruption in service". For homes, take 150 litres per head per day. For other buildings, base it on the building's daily water demand (para 2.39).
The stated reason for that 24-hour store is "to allow for disruption in service". Where a station has much less storage, a power cut or a failed pump leaves little time before it backs up, so a fast response to the high-level alarm matters more. A station that alarms often is worth raising with the client.
How often
| Where the station is | Interval |
|---|---|
| Commercial premises | Every 3 months |
| Multi-residential buildings | Every 6 months |
| A single house | Once a year |
Grundfos's Multilift MSS instructions give the same yearly check for single-family houses, carried out by authorised personnel and covering electrical and mechanical maintenance. BS EN 12056-4 itself is a paid standard; we quote the manufacturers' published summaries of it.
| After | Task |
|---|---|
| 3 months | Visual inspection of the inlet pipe; clean it if needed |
| 6 months | Check the connections are watertight; clean the collection tank and overflow channel (monthly if overflows happen regularly) |
| 1 year | Clean the solids separation tanks and screens |
| 2 years | Change the oil in the sewage pump |
The service visit
Packaged lifting station
From the Grundfos Multilift MSS instructions (section 9). The MSS is a single-pump station for small buildings such as houses and flats; a larger or duplex station has its own manual, which comes first.
- Inlet, outlet and vent connections tight and not leaking; pipe weight supported, not resting on the tank.
- Power consumption within the nameplate figure.
- Cable entries watertight; cables not sharply bent or pinched.
- Pump vent hole clear, checked with the pump off its support flange: undo the clamps, do not loosen the flange from the tank. Grundfos recommends a new O-ring between pump and flange.
- Test run with clean water; noise, vibration or abnormal running reported.
- Non-return valve, where it needs cleaning: close the isolating valves in the outlet and inlet pipes, or drain the outlet pipe, first, so the rising main does not empty through the cover. Clean it through its inspection cover and fit a new cover gasket.
- Controller: cover and cable entry gaskets, cable connections, functions, and the level sensor's pressure tube cleaned of deposits. The 9 V backup battery, if fitted, replaced at the annual service.
- Shaft seal, O-ring and oil checked. Grundfos says this work "must be carried out by the manufacturer or an authorised service workshop".
Submersible sump pump in a pit
From the Grundfos Unilift AP12, AP35 and AP50 instructions (sections 3, 7 and 8). This is a drainage pump: Grundfos says it is not suitable for sewage (section 6.2). A sewage pump in a pit has its own manual and intervals.
- Check the pump and replace the oil once a year. Check more often if it pumps liquid with abrasive particles or runs continuously.
- If the drained oil has water or dirt in it, replace the shaft seal.
- Float switch free and set right, with the stop level above the pump inlet so the pump does not draw in air. If the float switch keeps the pump from starting, adjust or replace it.
- A pump that runs constantly or gives too little water may be partly blocked, or its outlet pipe or valve may be.
| Liquid temperature | Replace the oil after |
|---|---|
| 20 °C | 4,500 operating hours |
| 40 °C | 3,000 operating hours |
| 55 °C | 1,500 operating hours |
Every item, with its source, is in our pump service checklist.
Working safely
- Stay out of the well if you can. The Confined Spaces Regulations 1997 name chambers, tanks, pits, sewers and wells among the places that can be confined spaces. HSE says to avoid work in confined spaces wherever possible; where it is not possible, assess the risks, plan how to control them and have emergency arrangements. Do not rely on the emergency services to get someone out.
- Treat the tank as an explosion risk. Wilo's EMUport CORE instructions warn of a potentially explosive atmosphere in the collection tank, treat a 1 m radius around the vent pipe as zone 2, and ask for eight air changes an hour in the room during maintenance.
- Flush before you open it up. Grundfos asks for the station to be flushed with clean water and the outlet pipe drained before work, and the parts rinsed after dismantling.
- Protect against infection. HSE lists plumbers among the workers whose health may be at risk from sewage, with illnesses including gastroenteritis, leptospirosis (Weil's disease, spread by rat urine) and hepatitis. Most infection comes from hand to mouth. It points to waterproof gloves, footwear, eye protection and face visors, washing facilities with clean water, soap, nailbrushes and paper towels, and sterile waterproof dressings for cuts. Keep contaminated kit apart from where you eat (INDG198).
- Isolate and lock off. Make the station dead and secure it so it cannot be switched on during the work (Electricity at Work Regulations 1989, regs 12 and 13). Do not take a quiet pump as stopped: the Multilift MSS controller runs a test start 24 hours after the last run. Wilo says only a qualified electrician does the electrical work.
- Close the valves. Grundfos asks for the isolating valves to be closed before work on a lifting station.
- Do not work alone where it matters. HSE gives confined space work, where a supervisor and someone dedicated to rescue may be needed, and work near exposed live conductors as examples where at least one other person may need to be present. Agree how you keep in touch on any lone visit (INDG73).
Worked example: a restaurant and its car park
The plant: a restaurant with basement toilets and kitchen drainage pumped by a packaged duplex lifting station, and a single submersible drainage pump in a sump pit taking surface water from the service yard. Both are on one contract. Kitchen drainage in commercial hot food premises should have a grease separator or other effective grease removal (Approved Document H, para 2.21), and the Grundfos Multilift MSS manual says not to discharge large amounts of greasy water, such as from deep fryers, into a lifting station (section 3.1). Check the separator is there and being emptied, and note any grease build-up in the tank or on the level sensor.
- Every 3 months (commercial premises): lifting station service: connections, inlet pipe inspection, non-return valves, level sensor, controller, high-level alarm and a test run of each pump in turn. Check the sump pump's float and run it.
- Every 6 months: add the collection tank and overflow channel clean where the station's instructions ask for it.
- Every 12 months: add the sump pump oil change and check, and the controller backup battery if fitted.
- As the manufacturer sets: oil changes and shaft seal work on the lifting station pumps, by the manufacturer or an authorised workshop where the instructions say so.
Grundfos asks for deposits on the level sensor's pressure tube to be checked and scraped off. Note what you find at each visit, with a photo, so the client sees the trend.
Who does what
- The owner or operator of the station keeps the log, reports alarms and agrees the service frequency.
- The maintenance contractor services the station to the manufacturer's instructions, records readings and faults, and signs the log.
- The manufacturer or an authorised workshop does the work the instructions reserve for them, such as shaft seal and oil work on some pumps.
- The employer of anyone who works in a confined space must make sure the Confined Spaces Regulations are complied with for that work; a self-employed engineer must comply for their own work (reg 3).
What to record
Wilo's instructions ask for all maintenance and repair work to be written in a log, signed by the qualified person and the operator, and for a test run after the work. For each visit, record:
- the station, each pump's make, model and serial number, and running hours;
- motor current against the nameplate;
- pass or fail for connections, non-return valves, level sensor, controller and the high-level alarm;
- oil condition and any oil change;
- what was cleaned, faults found, how urgent they are, parts used, and photos;
- the operator's signature.
Running pumping station contracts in Field Suite
- Equipment register: each station and pump at its site, with its service interval and job history, and a QR label on the panel that opens its page.
- Contracts: visits every set number of months, so 3-, 6- and 12-month visits each get their own line with a form attached, booked ahead of time.
- Pump service checklist: a ready-made form in the library with float switches and level controls, the high-level alarm, the control panel and non-return valves. The customer signs on the engineer's phone.
- Faults to quotes: a fault marked "Needs doing now" alerts the office straight away, and the office turns faults into a quote.
See pump maintenance software, read booster set servicing, check prices, or book a demo.
Field Suite is job management software. The manufacturer's instructions and the site's own risk assessments decide how a pumping station is serviced.
Sources
- Approved Document H: Drainage and waste disposal, 2015 edition, for use in England, para 2.21 (page 14) and paras 2.36 to 2.39 (page 16). https://assets.publishing.service.gov.uk/media/5a80cf9ded915d74e33fc8ae/BR_PDF_AD_H_2015.pdf
- Wilo, EMUport CORE installation and operating instructions, maintenance and repair, and safety. https://cms.media.wilo.com/dcianimpfinder/wilo747227/10345479/en-GB/21065007472106519435.html
- Grundfos, Multilift MSS installation and operating instructions, ss.3.1, 5.2, 8 and 9. https://api.grundfos.com/literature/Grundfosliterature-5247333.pdf
- Grundfos, Unilift AP12, AP35, AP50 installation and operating instructions, ss.3.2.5, 6.2, 7 and 8. https://api.grundfos.com/literature/Grundfosliterature-3279044.pdf
- HSE, Introduction to working in confined spaces. https://www.hse.gov.uk/confinedspace/introduction.htm
- Confined Spaces Regulations 1997, regulations 1 and 3. https://www.legislation.gov.uk/uksi/1997/1713/regulation/1 and https://www.legislation.gov.uk/uksi/1997/1713/regulation/3
- HSE, Protecting lone workers: How to control the risks of working alone, INDG73(rev4). https://www.hse.gov.uk/pubns/indg73.pdf
- HSE, Working with sewage: the health hazards. A guide for employers, INDG198. https://www.hse.gov.uk/pubns/indg198.pdf
- Electricity at Work Regulations 1989, regulations 12 and 13. https://www.legislation.gov.uk/uksi/1989/635/regulation/12 and https://www.legislation.gov.uk/uksi/1989/635/regulation/13
Last checked: 5 November 2026 against the sources above.
Field Suite is job management software for UK building services firms, not a consultancy. Your own risk assessments, contracts and advisers decide what applies to your work. Spotted a mistake? Email info@fieldsuiteapp.com and we correct it.