Bathrooms & Wet Rooms
Macerator installation
TL;DR
A macerator fitted to a WC in a loft, basement or garden room is £450–£850 all-in (unit plus labour), and takes 3–5 hours. They work brilliantly when there's genuinely no gravity route, but they're always a compromise — noisier, need power, and can fail if the wrong things go down them. If a proper 100mm gravity soil route is physically possible, always fit that instead. Where it isn't, Saniflo or SFA are the industry standard.
A macerator is an electric pump with a shredding blade that takes waste from a WC, basin, shower or bath and pushes it up (or across) through a small 22–32mm pipe to reach the main soil stack. It exists because sometimes there's just no route for a proper 100mm gravity soil pipe — a basement WC, a loft en-suite miles from the stack, or a garden-room shower with nowhere to go.
This page covers when a macerator is genuinely the right answer, when it isn't, and what a proper install looks like — because a bad macerator install is one of the most miserable things you can have in a house.
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When is a macerator the right answer?
When there's no possible gravity route to the soil stack. That usually means: a basement WC below stack level, a loft en-suite far from the main stack, a garden room / annex that isn't plumbed at 100mm, or an extension where lifting the floor slab is impossible. In every other case, gravity waste is quieter, more reliable, and easier to service — always fit that if you can.
- Basement or below-ground bathrooms
- Loft en-suite conversions with no direct stack access
- Garden rooms and detached annexes
- Ground-floor extensions on a slab with no soil route
- Utility rooms wanting an added WC
What we install — units matched to the job
Not all macerators are equal. A Sanicompact behind a small WC in a cloakroom is a very different unit from a Sanibest Pro handling a full family bathroom. Getting the right unit is the difference between 15 years of quiet operation and 18 months of nightmare.
- Sanicompact — WC-only, compact cloakroom, single-user
- Sanipro Up — WC + basin, small en-suite
- Sanibest Pro — WC + basin + shower + bath, heavy family use (2000W motor)
- Sanishower / Sanivite — shower, basin, kitchen sink only (no WC)
- Sanicubic — commercial or below-ground main-drain lift station
What a proper macerator install includes
We size the unit to the fixtures it will serve, run a dedicated 3A fused spur (macerators must not share a circuit with lights or a shower), fit an isolator switch outside the room, run the discharge pipe in solvent-weld 22mm or 32mm with continuous rise then fall at 1:100 minimum, add a non-return valve, and pressure-test the discharge before commissioning. Access for cleaning and future service is designed in from the start — a macerator that gets bricked into a stud wall is a maintenance disaster.
Before you commit — questions to ask any plumber
A badly installed macerator is a source of years of misery — smell, noise, and blockages. Ask these before you agree.
- Have you sized the unit to my actual fixtures, or is it one-size-fits-all?
- Will there be an access panel to reach the macerator for future service?
- Is the discharge pipe on its own run, not shared with a gravity waste?
- Is the electric feed a dedicated fused spur, not spurred off the ring main?
- Are you fitting a non-return valve to stop back-flow?
- What warranty comes with the unit (usually 2 years) and with your fitting (should be 12+ months)?
- Have you registered the unit with the manufacturer for the warranty?
Rules of life for anyone with a macerator
Even a perfectly installed macerator can be killed inside a year by the wrong things going down it. Share these rules with the household before you switch it on.
- Nothing goes down it except human waste, toilet paper, water and washing soap
- No wet wipes — even 'flushable' ones are not flushable through a macerator
- No sanitary products, cotton buds, dental floss, cat litter or nappies
- No cooking fat down a Sanivite (kitchen units)
- Descale every 6 months with the manufacturer's descaler (not bleach)
Typical prices
Real-world ranges from recent Northwest jobs. Your final price is confirmed in writing before any work starts.
| Item | Typical price | Notes |
|---|---|---|
| Sanicompact WC unit — supply & fit | 480 – 680 | Small cloakroom, 3–4 hours |
| Sanipro Up (WC + basin) — supply & fit | 620 – 880 | Small en-suite, 4–5 hours |
| Sanibest Pro (full bathroom) — supply & fit | 780 – 1,150 | Family bathroom, 5–6 hours |
| Sanishower / Sanivite — supply & fit | 480 – 720 | Shower or kitchen only, no WC |
| Dedicated fused spur + isolator (electrician) | 120 – 220 | Part P certificate included |
| Long discharge run (per additional metre) | 35 – 55 | Beyond first 4m included |
| Descale service visit | 85 – 125 | Recommended every 6–12 months |
| Emergency call-out (blocked unit) | 95 – 165 | Callout + first hour, parts extra |
Kit & brands we use
We fit Saniflo (SFA) as our default because parts are stocked at every UK plumbers merchant and warranty support is reliable. We also fit SFA Sanicubic for larger installs, and Grundfos SoloLift+ where a heavier-duty pumped-waste solution is needed. We do not fit no-name imported units.
Macerator red flags
- Fitter says 'any macerator will do' without sizing to your fixtures
- No access panel planned for future service
- Discharge pipe shared with an existing gravity waste (illegal and won't work)
- Electric spurred off the ring main instead of on its own fused spur
- No non-return valve on the discharge
- No advice given on what can and cannot go down it
- Quoting a macerator when a gravity route is genuinely available
Our promise on this job
Flat £50 diagnostic — deducted in full from any work booked. Fair, transparent quote before we start. If we can't fix the fault we diagnosed, we refund the diagnostic. All gas work is signed off by a Gas Safe registered engineer.
Talk to KJ about macerator installation
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