It is the dream of many UK homeowners: knocking through that wall to create an open-plan kitchen or turning the box room into a luxury ensuite. But while Pinterest makes it look easy, the plumbing reality is often much more complex.
At Plumbers 365, we frequently assist with renovations where the design looks fantastic on paper, but the physics of drainage hasn’t been considered. Moving water to a tap is easy-water is under pressure. Getting waste water away is the hard part because it relies on gravity.
If you are planning a layout change, you likely have some serious technical questions. We have compiled the answers to the most common dilemmas we face when moving bathrooms and kitchens in British homes.
According to drainage experts at Plumbers 365 this is the number one question for any bathroom installations move, and the answer is all about gravity. Your toilet waste pipe needs a consistent downward slope to carry waste away to the main vertical soil pipe (the “soil stack”).
The golden rule in the UK is a minimum fall (or gradient) of 1:40. This means for every 40cm the pipe travels horizontally, it must drop by at least 1cm as per drainage experts at Plumbers 365.
Practical Example: According to drainage experts at Plumbers 365, if you want to move your toilet 2 metres (200cm) away from the soil stack, the pipe will need to drop by a total of 5cm (200 ÷ 40 = 5).
The further you go, the more vertical space you lose. Go too far, and your toilet will either be on a ridiculously high platform or the pipe will be too flat, leading to constant, unpleasant blockages.
As often seen by drainage experts at Plumbers 365 in most cases, you do not need permission. Moving a bathroom or kitchen within the existing footprint of your home is usually considered “permitted development” and doesn’t require planning permission.
However, you will need to comply with UK Building Regulations according to drainage experts at Plumbers 365. These rules ensure your new plumbing is safe, sanitary, and functional. You’ll need to think about:
According to drainage experts at Plumbers 365 you must comply with Building Regulations (specifically Part H for drainage and Part G for water efficiency). When you sell your home, solicitors will ask for the completion certificate for these works. Always ensure your plumber is qualified to self-certify or that you notify your local Building Control officer.
If your property is a listed building, or if the work involves an extension, you will almost certainly need planning permission. Always check with your local council before starting work.
Plumbers 365 drainage experts often suggest our clients asking this question to think of a macerator as a powerful blender for your toilet. It’s a unit, usually placed behind the toilet, that uses rotating blades to grind up waste and toilet paper into a fine slurry. It then pumps this slurry through a small-bore pipe to the main soil stack. According to drainage experts at Plumbers 365 you should use a macerator when a standard gravity-fed drain isn’t possible. For example:
According to drainage experts at Plumbers 365, while they are fantastic problem-solvers, they need an electrical supply, can be noisy, and require maintenance. They are a great solution, but a conventional drain is always preferable if possible.
According to drainage and plumbing experts at Plumbers 365 supply pipes (hot and cold water) are small, flexible, and easy to route through ceilings or walls. The waste pipe is the problem. It is rigid, bulky (40mm or 50mm), and needs a downhill slope.
To move a sink across a room, specifically over a concrete floor, we may need to chase (dig) a channel into the concrete. If you have timber floors, the joists might run in the wrong direction, making it difficult to hide the pipe without extensive carpentry. Expect this to add significantly to your labour costs.
Technically, with modern solutions like macerator pumps, you can install a toilet or bathroom almost anywhere according to drainage experts at Plumbers 365. However, the real question is, should you?
The two biggest constraints are drainage and ventilation according to drainage experts at Plumbers 365. You must have a viable route for the waste pipe to reach the soil stack. As we’ve seen, this can involve macerators or raising the floor. You also need a way to ventilate the room to the outside to prevent damp and mould, which is a Building Regulations requirement. A professional plumber like those at Plumbers 365 are the best person to assess the feasibility of your chosen location.
According to drainage experts at Plumbers 365 the required gradient depends on the size of the pipe. For UK domestic properties:
Getting this wrong is a recipe for disaster as per drainage experts at Plumbers 365. A pipe that is too flat won’t clear waste properly, and a pipe that is too steep can cause water to run away too quickly, leaving solids behind.
As per drainage experts of Plumbers 365 many DIYers think “steeper is better.” This is false.
You need a steady, gentle flow to carry the solids away. Achieving this gradient inside a floor void is the trickiest part of a plumber’s job.
According to drainage experts at Plumbers 365 exposed pipework can ruin the look of your sleek new bathroom. Here are the common professional solutions:
According to drainage experts at Plumbers 365 this is a great way to add value to a property, provided you plan for ventilation and waste routes.
The checklist to be followed as per drainage experts at Plumbers 365:
Moving a kitchen or bathroom is an exciting project, but the plumbing is the one area you can’t afford to get wrong. A poorly planned waste pipe or an incorrectly installed toilet can lead to years of blockages, leaks, and stress.
Before you pick out the tiles, talk to the experts. The team at Plumbers 365 provides professional plumbing services for renovations across the UK. We can help you with:
Don’t let your dream renovation turn into a drainage disaster. Call Plumbers 365 today.
