What is a Saniflo and when do you need one?

An ordinary toilet relies on gravity to carry waste down to the drain, which only works if the toilet sits above the level the drain run needs. In a basement, a loft conversion, or a downstairs cloakroom added under the stairs, that is often not the case — which is where a macerator unit, commonly known by the brand name Saniflo, comes in.

How it actually works

A Saniflo sits behind or beside the toilet and macerates waste into a fine slurry, then pumps it, under pressure, along a narrow pipe to the nearest suitable drain or soil stack — which can be some distance away and does not need to be below the toilet, unlike a gravity connection. That is what makes it possible to add a toilet almost anywhere in a house, regardless of where the existing drainage happens to run.

Where it gets used

• Basement and cellar conversions, where the drain run is above the new room, not below it.
• Loft conversions, where running a full gravity soil pipe down through the house is impractical.
• Under-stairs cloakrooms and extensions, where there is no nearby gravity connection at all.

See Saniflo and macerator pumps for the range of units this covers, including where a smaller unit is enough for just a toilet versus a full unit handling a basin and shower too.

What tends to go wrong

The most common issue is a blockage from something that should never have gone down it — wipes, sanitary products, anything not genuinely flushable — since the macerator blades are not designed to handle it. A unit that hums but does not clear, or that has started running longer than usual, is usually asking for a service or a descale rather than a full replacement.

If you are planning a new bathroom or cloakroom where the drainage is awkward, our bathroom installation and toilet installation pages cover the wider job, and our drainage services page explains when ordinary gravity drainage is possible after all.