A macerator is an apparatus designed to mash, pulverise, pulp, slice and churn human waste from a solid into a liquid so it can be pumped away to the sewer.
The macerator's internal parts include:
- Pump
- Rotating blades, up to 3,600 RPM
- Microswitch
- Membrane
- Non-return valve
- Impeller
When the toilet is flushed, the waste is directed into the macerator rather than straight into the sewer. The wastewater rises and triggers a microswitch, which activates the macerator.
The blades rotate at high speed, reducing solids to a liquid slurry. Once the cycle is complete, the slurry is pumped away through the discharge pipe and into the sewer.
For more information on toilets, drains, blockages and Saniflo systems, see our guide to toilets, drains, blockages and Saniflo systems.
Where Can a Macerating System Be Installed?
You may want to install an additional WC in an ensuite bathroom, utility room, under the stairs, basement or extension where conventional plumbing cannot reach the soil stack.
A macerator can also be connected to a sink, shower or bidet. Greywater from sinks, showers and washing machines can also be discharged through some systems.
There are many makes and models available, depending on your requirements. Manufacturers such as Saniflo, Grundfos, Stewart and Turner produce macerators for different applications.
If you are confident with household plumbing, you may feel able to install a macerator yourself. However, you will need to plumb in the macerator, provide a suitable electrical supply and fit RCD protection for the circuit.
If your skills do not cover electrical installation, this part should be left to a professional. If Serviceteam completes the installation, the materials and workmanship are covered by warranty.
How to Install a Macerator
Before starting, be realistic about whether you are confident enough to install a macerator yourself or whether it is better to use a professional plumber.
You will need to plan the position of the macerator, the discharge pipe run, water supply and electrical supply before beginning the installation.
Macerator Installation Checklist
You will need:
- A macerator suitable for the installation
- A suitable water supply with sufficient pressure
- A discharge pipe of the diameter specified for your model — typically around 22mm for a standard WC macerator, though this varies between manufacturers
- An electrical supply with RCD protection
The macerator usually fits behind the newly installed WC.
Distance from the nearest soil stack is also important. Maximum recommended distances vary considerably between macerator models and pump sizes, so always check the specific manufacturer's technical guidance rather than relying on a single figure.
Every pump has its limits. If the system is pushed beyond its capabilities, it may need to be re-routed, re-piped or re-sited. Getting the position and pipe run right from the start can help avoid these problems.
Connect the Discharge Pipe
First, access the main soil stack to connect the discharge pipe from the macerator.
A suitable-sized connector is inserted into the soil stack to accept the discharge pipe. The discharge pipe is then connected so that waste from the macerator flows into the soil stack and down into the sewer.
Alternatively, instead of teeing into the soil stack, a macerator strap-on boss connector can be used to make the discharge connection.
Make sure every connection is secure and leak-free.
If the discharge pipe is plastic and the run is long, support the pipe with clips or brackets. Plastic pipe can sag or belly over a long run, allowing debris to collect and potentially causing a blockage.
Simply clearing the blockage will not solve the underlying problem if the pipe run remains unsupported.
Connect the Water Supply
Connect the WC cistern to a suitable water supply.
The flush works in the same way as a conventional WC, but the wastewater passes through the macerator. This activates the microswitch and starts the blades, which shred the waste before the impeller propels it towards the drain.
Cut into the water supply, insert a suitable adapter, run the pipe to the macerator and connect it. Cold water is suitable.
Connect the Power Supply
The macerator needs a suitable nearby electrical connection. This should not be a conventional plug and socket. A wall-mounted fused connection unit is generally recommended, wired to a standard UK 230V single-phase AC 50Hz supply with RCD protection.
The exact electrical requirements can vary between macerator models, so check the manufacturer's technical guidance before connecting the system.
Tips for Installing Macerator Pipe Runs
A well-planned pipe run is important for reliable operation.
Keep bends gradual and avoid sharp turns in the discharge or vent pipe. A common mistake when running macerator pipework is using 90-degree elbows. These create a tight turn that can increase the risk of blockages.
Where possible, use 45-degree elbows or long-turn fittings. These create a gentler change of direction. Fewer bends are also preferable.
Horizontal pipe runs generally need a minimum fall of 1:100, or 10mm per metre, towards the soil stack, though you should check the specific figure for your model.
If a vertical lift is required, it must be made before the horizontal run at the start of the pipe run.
If the macerator is installed against an external wall, particularly in a basement, protect it against freezing temperatures. Lagging the macerator can help protect it, especially where the property will be left vacant during winter.
Always isolate the electrical supply before carrying out maintenance, removing blockages or replacing parts.
Need Help Installing a Macerator?
If you run into difficulties installing a macerator, Serviceteam can help. Our qualified professionals specialise in macerator installations and can advise on the installation and pipework.
If the problem is an existing blocked toilet or sink rather than a new macerator installation, Serviceteam also offers a fixed-price toilet and sink unblocking service. If your existing macerator is faulty rather than being newly installed, our macerator repair service may be more appropriate.
Need help installing a macerator? If you're unsure about the pipe run, soil stack connection or electrical requirements, Serviceteam can help with macerator installation. Get in touch to discuss your requirements and arrange professional help.
