How to Install a New Toilet: A UK Homeowner's Guide
- Luke Yeates
- Sep 28
- 17 min read
Swapping out an old toilet is one of those home improvement jobs that seems daunting but is actually quite achievable. It really boils down to four key stages: getting the area ready, removing the old loo, setting the new one in place, and then hooking everything up. With the right kit and a bit of patience, you can get a professional, leak-free finish in just a couple of hours.
Your Pre-Installation Game Plan and Checklist
A good toilet installation starts well before you even think about picking up a spanner. Believe me, solid preparation is the secret to avoiding those frantic, mid-job dashes to the DIY shop or the horrible realisation that your new toilet doesn't quite fit. It’s the exact approach our engineers at Harrlie Plumbing and Heating take, whether we're working in a modern flat near Sovereign Harbour or a Victorian terrace in Meads. A bit of planning saves a lot of headaches.
First things first: safety and water. You absolutely must shut off the water supply to the toilet. Look for a small isolation valve on the pipe behind the loo and give it a quarter-turn. If there isn't one, or it's seized solid (which happens a lot in older Eastbourne homes), you'll need to shut off your home's main water supply.
Understanding Your Existing Setup
Before you can pick a shiny new toilet, you need to know what you're dealing with. In the UK, you’ll typically find one of a few common styles, and each has its own plumbing quirks.
Close-Coupled Toilets: This is what most people have. The cistern sits directly on the back of the bowl, making a single neat unit. They're generally the most straightforward to replace. We see these everywhere, from new builds in Willingdon to family homes in Langney.
Back-to-Wall Toilets: With these, the pan is flush against the wall and the cistern is hidden, either in the wall itself or a cabinet. Replacing these can be a bit more of a puzzle.
Low-Level Toilets: Common in older Eastbourne properties, these have the cistern fixed to the wall just above the bowl, connected by a short, exposed pipe.
Knowing your toilet type is crucial. It helps you buy a replacement that will line up with your existing waste pipe and water feed, which means less faffing about with extra plumbing work later on.
Taking the Critical Rough-In Measurement
If you only take one measurement, make it this one: the rough-in. This is simply the distance from the wall behind the toilet to the dead centre of the waste pipe coming out of the floor.
Pro Tip: Don't measure from your skirting board! You need to measure from the actual wall to get an accurate figure. The standard UK rough-in is about 305mm (12 inches), but at Harrlie Plumbing and Heating, we've seen all sorts of variations in older Eastbourne houses. Buying a toilet with the wrong rough-in means it either won't fit at all or you'll be left with a massive, dust-collecting gap behind it.
Assembling Your Toolkit
Getting all your tools and materials in one place before you begin is a game-changer. It turns a potentially chaotic job into a smooth, methodical process. Think of it as setting up your mission control.
To give you a head start, here’s a checklist of the essential tools and materials you'll need for a successful DIY toilet installation. This is the standard kit our Harrlie Plumbing and Heating team would bring to any toilet replacement job in Eastbourne.
Essential Tools and Materials for Toilet Installation
With these items gathered and a clear plan in mind, you're well on your way to a successful installation. Taking the time to prepare properly now will make the entire process smoother and more satisfying.
Removing Your Old Toilet Without the Mess
Right, with your tools laid out and the new loo waiting in the wings, it's time to get the old one out. This is the part that worries most people – the potential for a watery mess. But if you’re methodical, you can keep the spills and stress to an absolute minimum. Getting this bit right is all about controlling the water and lifting safely. It sets the stage for a smooth installation.
First things first, and this is non-negotiable: turn off the water. As we mentioned, use the small isolation valve behind the toilet or shut off the main stopcock for the house. Once you’re absolutely sure no more water is getting to the cistern, give it a good flush. Hold the handle down to let as much water as possible drain away.
Even after a thorough flush, you’ll find a surprising amount of water left sloshing around in the cistern and lurking in the S-bend of the bowl. This is where those old towels and your bucket really earn their keep. A big sponge or, even better, a wet/dry vac will be your best friend here. Your goal is to get every last drop out to avoid a mini-flood when you lift the toilet away.
Disconnecting the Water and Fixture
With the water sorted, let's get everything disconnected. The water supply pipe – usually a flexible hose or sometimes a rigid copper pipe – needs to be detached from the bottom of the cistern. Grab your adjustable spanners for this. Use one to hold the inlet valve steady inside the cistern and the other to carefully undo the connecting nut. It's always a good idea to keep your bucket handy underneath to catch the inevitable drips.
Next up are the bolts holding the toilet to the floor. If you're in a newer build, these will probably come off without much of a fight. However, in many of the older Eastbourne properties we work on at Harrlie Plumbing and Heating, these bolts can be rusted solid.
We see this all the time, especially in coastal homes from the seafront to Pevensey Bay where the salty air can accelerate corrosion. If the nuts won't budge with a spanner, don't force them and risk cracking the porcelain. A good penetrating oil can help, but often the quickest solution is to carefully cut them off with a small hacksaw or a multi-tool.
Once the floor bolts are free, have a look behind the cistern. It's common, particularly with close-coupled toilets, for it to also be secured to the wall with a couple of screws. Remove these, and your toilet should now be completely free.
The Safe Lift and Old Seal Removal
Now for the grunt work. A porcelain toilet is deceptively heavy and awkward. The best way to lift it is to stand over the bowl, get a firm grip under each side, and lift with your legs, not your back. You'll probably need to give it a gentle rock back and forth to break the old wax or foam seal that’s been compressed underneath it.
When you feel the seal release, lift the whole unit straight up and move it onto the old towels or cardboard you've laid down. You’ll be greeted by the exposed waste pipe and the remnants of the old, squashed wax ring. This gunk needs to come off completely. Use a putty knife or an old scraper to get every last bit. Any residue left behind can stop your new seal from seating properly and cause leaks down the line.
Responsible Disposal in East Sussex
You can’t just chuck an old toilet in your wheelie bin. It's classed as sanitary ware, and local councils have specific rules for getting rid of it. For anyone in the Eastbourne area, you've got a couple of simple options:
Household Waste Recycling Sites: Your local tip will have a dedicated skip for this kind of waste. You can take your old toilet to the Eastbourne Household Waste Recycling Site on St Philip's Avenue. It's always worth checking the East Sussex County Council website for opening times and to see if you need to book a slot.
Bulky Waste Collection: If you don't have a car big enough, most councils, including Eastbourne Borough Council, offer a collection service for large items. There's a small fee, but it can save you a lot of hassle.
Disposing of it properly means you've ticked off the first major part of the job cleanly and responsibly. You're now left with a clear, prepped space, ready to get the flange ready for your new toilet.
Getting the Flange Ready for a Perfect Seal
With the old loo out of the way, your attention now turns to the most critical part of the whole operation: the toilet flange. This is the ring on the floor that connects your toilet to the waste pipe, and getting this stage right is everything. It’s the difference between a solid, leak-free installation and a wobbly toilet with foul odours and water damage down the line.
Your first job is to get it completely clean. Grab a putty knife or a plastic scraper and carefully remove all the old, sticky wax from the ring. Don't be afraid to be firm, but take care not to gouge the flange itself or the surrounding floor. Once the worst of it is off, a rag dampened with a bit of white spirit will help get rid of the last stubborn bits of residue.
A clean surface is non-negotiable because it lets you see what you’re really working with.
Giving the Flange a Proper Inspection
Now you can have a good look at the condition of the flange. You're hunting for any red flags that could ruin your new toilet's seal.
Look for cracks or breaks. Pay close attention to the slots where the bolts sit. A fractured flange won’t hold the toilet securely and is a future leak just waiting to happen.
Check for corrosion. If you've got an older cast iron flange, check for heavy rust that might have compromised its strength.
Inspect the bolt slots. Make sure they're solid. If the channels are broken out, you won't be able to tighten the toilet down properly.
If you find any serious damage, stop right there. A broken flange has to be repaired or replaced before you can continue. This is where a simple DIY job can get a lot more complicated, and it might be the right time to give a professional at Harrlie Plumbing and Heating a ring.
A very common problem we see, especially in the older housing stock around Eastbourne – from Victorian terraces in Old Town to the 1930s homes in Hampden Park – is the flange sitting below the level of the finished floor. New flooring like tiles or laminate gets laid over the years, and suddenly the flange is recessed.
This height difference is a big deal. If the flange is too low, the wax ring won't compress enough to create a watertight seal. Luckily, this is usually a straightforward fix.
Sorting Out Flange Height Problems
If your flange is sitting below the floor, you've got a couple of solid options that don't involve major plumbing work.
Flange Extenders: These are basically plastic spacer rings that stack on top of your existing flange. They come in different thicknesses to bring the flange height up to be level with, or just above, the floor. They’re a quick and reliable solution.
Thick Wax Rings: You can also buy extra-thick wax rings, often with a plastic horn built in. These are specifically made for slightly recessed flanges, giving you that extra bit of wax you need to squish down and form a tight seal.
Once the flange is clean, solid, and at the right height, you're nearly there. Stuff a large rag into the opening of the waste pipe. This is a crucial little step – it stops nasty sewer gases from coming up and, just as importantly, prevents you from dropping a spanner or a bolt down the drain. A simple tip, but dealing with blockages is a massive pain. If you do run into trouble, our guide on how to unblock a waste pipe for Eastbourne homes has some good advice.
Finally, slide the new closet bolts into the slots on the flange, with the threads pointing straight up. Make sure they’re parallel to the wall behind the toilet and spaced correctly to match the holes on the base of your new loo.
With a perfectly prepped flange, you’re ready for the main event: setting the new toilet in place.
Setting and Securing Your New Toilet Like a Pro
Right, the groundwork is done. Now for the satisfying bit: actually placing your new toilet. This is where all that prep work really pays off. Getting the seal right and locking the bowl down securely are the last big steps to a professional, leak-free finish that will serve you well for years to come.
Your first decision is a small but critical one. Are you going with a traditional wax ring or one of the newer foam or wax-free seals? For decades, wax was the only game in town. It’s cheap and does the job, squishing down to create a watertight seal. The big drawback? It’s messy and a one-shot deal. If you have to lift the toilet for any reason, even slightly, that ring is toast and you’ll need a fresh one.
The Modern Seal Advantage
At Harrlie Plumbing and Heating, our engineers are fitting more and more modern foam seals on jobs across Eastbourne. They just make sense, especially in older properties where you can’t always count on the floor being perfectly level.
More Forgiving: You can reposition them without ruining the seal. This is a massive stress-saver if you don't nail the alignment on your first attempt.
Cleaner Installation: No more sticky, yellow wax on your hands, the floor, or the nice new loo.
Long-Lasting: Unlike wax, they won’t dry out or crack over time, which gives you a more reliable seal in the long run.
Whichever you’ve chosen, place the ring directly onto the flange. Your goal is to get it perfectly centred over the waste pipe. Now, take a deep breath—it’s time to set the toilet.
This image nails the core principle: position the ring, carefully lower the bowl, and tighten it down evenly. It’s the fundamental sequence for preventing leaks.
Stand over the flange, getting a firm grip on both sides of the new toilet bowl. Carefully line up the holes in the base with the bolts sticking up out of the floor. Lower the toilet straight down, doing your best to keep it level. The moment it makes contact, use your body weight to press down firmly and evenly. This is what compresses the seal. Whatever you do, don't twist or rock the toilet, as this will immediately break the seal you’ve just worked so hard to create.
Securing the Bowl without Cracking It
With the bowl sitting squarely on its new seal, you can bolt it down. Pop a washer and a nut onto each of the floor bolts. Now, here’s a tip I can't stress enough: tighten the nuts alternately. Give one side a few turns, then switch to the other. Back and forth. This ensures you’re applying even pressure across the base.
Overtightening is easily the most common mistake people make here. You’re aiming for snug and stable, not an all-out battle with the spanner. Cranking down with all your might is the quickest way to crack that fragile porcelain. The second you feel solid resistance and the toilet no longer wobbles, stop. This is a rule our Harrlie Plumbing and Heating engineers live by on every job in Eastbourne.
Once it's secure, you can use a small hacksaw to trim the excess length off the bolts. It’s a small touch, but popping the decorative plastic caps on top of a shorter bolt makes for a much neater finish.
Assembling the Cistern and Flush Mechanism
Now to build the top half. If your cistern and bowl came as separate pieces, you’ll need to connect them. Find the large rubber gasket—often called a 'doughnut' gasket—and fit it snugly over the outlet on the bottom of the cistern. With that in place, you can lower the cistern onto the back of the bowl.
You’ll have a couple of long bolts that go down through the cistern and the bowl, with rubber washers inside the cistern to stop leaks. Secure them with nuts from underneath. Just like before, tighten these alternately and evenly until the cistern feels solid and doesn't rock. To finish up, connect the flush mechanism to the handle or push-button, following the manufacturer’s guide.
While there’s a lot of satisfaction in doing this yourself, it’s also good to know when to call in a pro. Here in the UK, the cost to have a new toilet installed typically falls between £200 and £700. The average job comes in around £450, which usually covers both the toilet itself and the labour. An experienced plumber can get the whole thing done in about four hours, ensuring a perfect job. You can find out more about the breakdown of toilet replacement costs to see how things like your location and the type of toilet can affect the final price.
Finishing Up: Water Connections and Final Checks
You’re on the home stretch now. With the new toilet firmly in place, it's time to connect the water, run a few crucial tests, and add those finishing touches. This last stage is all about being methodical and patient. Taking your time here ensures every connection is watertight, saving you a world of trouble later on.
First things first, let's get that water supply reconnected. Most new toilets come with a fresh flexible hose, and my advice is to always use it. Old hoses can go brittle and are a common culprit for slow leaks that cause damage over time. It’s just not worth the risk.
Whether you're fitting a new hose or your old one is still in good nick, the method is the same. Start by hand-tightening the connection onto the inlet valve at the bottom of the cistern. Get it as snug as you can with just your fingers, then grab a spanner for a final quarter to half-turn. That’s it. Be careful not to go overboard here – over-tightening can easily crush the rubber washer inside, which ironically will cause the very leak you're trying to prevent.
A Plumber’s Trick for a Perfect Seal
When you're dealing with threaded connections, especially older metal pipework, PTFE tape is an absolute lifesaver. This thin white tape is brilliant for creating a completely watertight seal on the threads.
At Harrlie Plumbing and Heating, we make a point of wrapping the male threads with a few layers of PTFE tape before making any connection. The key is to wrap it clockwise – the same direction you’ll be turning the nut. This simple trick stops the tape from bunching up or unravelling as you tighten it. It’s a small detail, but believe me, it makes a huge difference in preventing the kind of annoying drips we’re often called out to fix in properties around Eastbourne.
Right, with everything connected, it’s the moment of truth. Head back to your isolation valve or the main stopcock and turn the water back on. The trick here is to do it very slowly. Just crack the valve open a fraction at first. This lets the pressure build up gently and gives you a chance to listen for the tell-tale hiss of an obvious leak before it becomes a spray.
The All-Important Leak Check
As the cistern begins to fill, it's time to play detective. You need to meticulously check every single connection point for any sign of moisture. My top tip is to use a piece of dry kitchen roll and wipe it around each nut and join. It’s far more effective than using your fingers and will instantly show up even the tiniest bead of water.
Be sure to check these key spots:
The water supply connection coming out of the wall or floor.
The point where the hose connects to the cistern's inlet valve.
The large nuts that secure the cistern to the toilet bowl.
Around the very base of the toilet, just in case the wax or rubber seal hasn't seated perfectly.
If you do spot a drip, don't panic. Turn the water off straight away and gently tighten the leaky connection another quarter-turn. It's quite common to have a small weep on the first try, and it's usually a quick fix.
Fine-Tuning the Flush and Finishing Off
Just listen as the cistern fills up. It should stop on its own once the water reaches the fill line, which is usually marked on the inside wall. If the water keeps running or doesn't fill up enough, you'll need to adjust the float mechanism. Thankfully, most modern floats have a simple screw or clip that makes raising or lowering the water level a doddle.
The very last job is to apply a neat bead of sanitary sealant around the base of the toilet where it meets the floor. This isn't just for looks; it provides a clean, professional finish and also stops any stray mop water from getting trapped underneath. Plus, it adds a bit of extra stability, preventing the toilet from shifting over time.
This kind of project is a fantastic way to upgrade your bathroom. It's a popular choice for homeowners, though the UK bathroom renovation market has had its ups and downs, with sales dipping by about 5% after the pandemic as budgets tightened. Still, forecasts are looking positive, predicting a modest 3-4% growth in the refurbishment sector. It just shows that people are still keen to invest in their homes. You can read more about UK bathroom market trends and forecasts on kbbreview.com.
Give the sealant a good 24 hours to cure properly, and that’s a wrap. You’ve just successfully installed a new toilet. Time to stand back and admire your handiwork.
Your Top Toilet Installation Questions Answered
Even the best-laid plans can hit a snag, and a hands-on job like fitting a new loo is no exception. We get calls from homeowners all the time here at Harrlie Plumbing and Heating, from first-timers in new builds to seasoned renovators working on Eastbourne's classic period properties.
Here are the answers to the questions we hear most often, designed to get you over those final hurdles.
Can I Just Reuse the Old Wax Ring?
I get why people ask this, but the answer from any professional, including our team at Harrlie Plumbing and Heating, is always a firm no. A wax ring is a one-shot deal. Its whole purpose is to compress and create a perfectly customised, watertight seal between the toilet and the waste pipe flange.
Once you lift that toilet, the seal is broken for good. Trying to reuse it is asking for trouble—it's one of the surest ways to end up with a slow leak that rots your subfloor or, worse, lets foul sewer gases into your bathroom. For the few quid a new one costs, it's just not worth the risk.
My New Toilet Wobbles—What Do I Do?
This is a classic problem. Your first instinct might be to tighten the bolts down as hard as you can, but please don't! You're far more likely to crack the porcelain base of your brand-new toilet than to fix the wobble.
A wobbly toilet almost always means your floor isn't perfectly level—a common quirk in Eastbourne's older Victorian and Edwardian houses. The proper fix is to use toilet shims, which are little plastic wedges made for this exact job.
Find where the gap is and gently slide the shims in until the toilet feels solid and doesn't rock at all.
Once you're happy with the stability, you can easily snap off the bits of the shims that are sticking out.
A clean bead of silicone sealant around the base will then hide them completely, giving you a professional finish.
This way, the toilet is supported evenly, preventing any stress on the ceramic.
What on Earth Is a 'Rough-In' Measurement?
The 'rough-in' is simply the distance from the finished wall (the plaster or tiles, not the skirting board) to the very centre of the waste pipe. This measurement is absolutely critical to check before you buy your new toilet.
The standard rough-in in the UK is typically 12 inches (about 305mm). However, we see all sorts of variations, especially in the older houses around Eastbourne and Meads. If you buy a toilet with the wrong rough-in, you'll either have a massive gap behind the cistern or it just won't fit, period.
A common pitfall we at Harrlie Plumbing and Heating see is when new, thicker tiles have been added to a bathroom wall. This can easily shrink the rough-in distance by half an inch or more, which is often enough to cause a problem. Always measure the space as it is right now.
When Is It Time to Call a Plumber?
Being a confident DIYer is great, but knowing your limits is even better. It's time to put the tools down and call a professional if you run into serious issues.
If you pull up the old toilet and discover the flange is cracked or broken, or that the subfloor is soft and rotten from an old leak, that's a job for an expert. Likewise, if the pipework itself needs to be moved or altered, don't take any chances. These problems require specialist knowledge and tools. If you need help finding the right person, our guide on finding a plumber in Eastbourne has some handy local advice.
If you've hit a roadblock or just want the peace of mind that comes with a professional job, Harrlie Plumbing and Heating is ready to help. Our team covers Eastbourne and the surrounding areas, guaranteeing a quick, clean, and leak-free installation. Pop over to our website at https://www.harrlieplumbing.co.uk to get a free quote.
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