Foul drainage: gravity or macerator
Where the garden room sits below or close to the level of the existing drainage run and reasonably near the house, a gravity connection - a conventional fall pipe running to the existing foul system - is usually the cheaper and more reliable option, and it's always our first choice where the levels allow it.
Where the room sits further away, at a similar or higher level than the drain, or the run would need to cross a driveway or existing landscaping, a macerator unit is the practical answer: it pulverises waste and pumps it, often through much smaller pipework, to the nearest connection point. Macerators are reliable but do need mains power and occasional maintenance, which we explain clearly before you decide.
Building regulations, ventilation and hot water
Any room with a shower and toilet falls under building regulations for drainage, ventilation and water supply regardless of the room's overall size, so we design in mechanical extract ventilation to the bathroom (a legal requirement, not an option) and a compliant hot and cold water supply run from the house or a local point-of-use water heater.
For a small shower room, a point-of-use electric water heater is often more practical than running a long hot water pipe from the house, since it avoids heat loss over distance and gives instant hot water at the point it's needed - we assess which suits your specific layout.
- Mechanical extract ventilation to the shower room, required under building regulations
- Foul drainage: gravity connection preferred, macerator where levels or distance don't allow it
- Point-of-use electric water heater or a supply run from the house, depending on distance
- Waterproof tanking and drainage falls built into the shower area from the structural stage
What it costs
A compact garden room with a shower and toilet, fully finished, typically starts from around £32,000, reflecting the drainage connection, tanking, ventilation and additional fittings over a standard garden room of the same size. A macerator connection over a gravity connection typically adds £1,500 to £3,000 depending on pump distance and pipe run.
We always survey the actual drainage route before quoting a fixed figure, since it's the one variable on this type of build that genuinely differs from plot to plot.
Where we build garden rooms with a shower and toilet
We design and build these rooms across Mid Sussex, the wider Sussex counties, Surrey and Kent, and always survey drainage runs and invert levels before pricing, since that's what actually determines cost on this type of build.
- Haywards Heath
- Cuckfield
- Lindfield
- Burgess Hill
- Horsham
- East Grinstead
- Reigate
- Oxted
- Tunbridge Wells
- Sevenoaks
Garden room shower and toilet questions
- Is a macerator reliable for a garden room toilet?
- Yes, modern macerator units are reliable and widely used for exactly this application. They do need mains power and occasional servicing, and we're upfront that a gravity connection is generally the simpler long-term option where levels allow it.
- Do I need building regulations approval for a shower room?
- Yes - drainage, water supply and ventilation for a room with sanitary facilities fall under building regulations regardless of the overall size of the garden room, and we manage that approval as part of the build.
- How do you get hot water to a garden shower room?
- Either a point-of-use electric water heater installed in the room itself, which avoids heat loss over a long pipe run, or a supply extended from the house where the distance is short enough to make that practical. We assess which suits your layout at survey.
- How much does drainage add to the cost?
- A gravity connection is usually the cheaper route where levels allow it. A macerator system typically adds £1,500 to £3,000 depending on pump distance and pipe run, which we confirm after surveying your specific drainage route.
- Can this be combined with a garden annexe?
- Yes, a shower and toilet room is often the starting point for a full annexe with a kitchenette added, though a full annexe used as a separate dwelling brings in planning permission requirements that a simple shower room on its own does not.
What our clients say
Reviews from homeowners across Sussex, Surrey and Kent.
"Best in class. None of my specific requests were any trouble at all. The team were polite, professional, smart, and accommodating throughout. A perfect example of how professional tradespeople should be."
"Alistair understood exactly how we wanted to use the garden. The finished space feels like a private retreat and we use it every day."
"Our garden office has completely transformed how we work from home. The quality is outstanding and the process was seamless."
Areas we cover
Designed and built by our own team across Sussex, Surrey and Kent.
West Sussex
East Sussex
Not on the list? See the full coverage map - we travel further for larger projects.
Read next
- Garden annexes: planning, regs and drainage explained
- How an insulated garden room is actually built
- Garden gyms with shower room options
- The full garden room collection and build process
Adding a shower and toilet to your garden room?
We'll survey the drainage route first, so the price you're quoted reflects the real cost of connecting your plot, not a generic figure.