Bathroom and Kitchen Renovations: Why Plumbing Should Come First
Planning a kitchen or bathroom renovation?
Homeworkers often want to skip to the exciting parts. Choosing tiles. Picking taps. Browsing Pinterest. But here’s the truth…
If plumbing issues are not addressed first, that lovely tile work and those high-end fixtures will give you problems later.
Plumbing is the framework for every kitchen and bathroom. Mess this up and you’ll be tearing out new tile to fix leaks, contamination or pressure issues within months of completing the project.
Here’s how to do it the right way…
What’s inside this guide:
- Why Plumbing Has To Come First
- The Real Cost Of Skipping Plumbing Checks
- Backflow Testing: The Step Most Homeowners Miss
- Plumbing Priorities For Kitchens
- Plumbing Priorities For Bathrooms
Why Plumbing Has To Come First
Here’s the thing about renovations…
Plumbing is sloppy work. It’s invasive and rarely can be done neatly after tile has been set and cabinets are screwed in place. Every design decision you make is going to go over the piping hidden in your walls.
According to a survey on recent renovations, 1 in 3 homeowners reported that their bathroom remodel went over budget. This is typically due to unforeseen plumbing upgrades, water damage, or structural repairs.
Did you know that 1/3 of remodelers exceed their budgets due to unforeseen plumbing issues that could have been detected early.
Getting a detailed plumbing inspection complete with backflow testing before any cosmetic renovations begin is your best protection. When you need reliable inspections and code-compliant plumbing, the professional services from Integrity Plumbing can spot unseen problems, perform backflow testing on your home and alert you to potential drainage issues well before the demo team arrives on scene. Backflow testing is something most renovators tend to overlook, so remember to include it in your timeline. It’s also one of those tasks where DIY will just not cut it.
The Real Cost Of Skipping Plumbing Checks
Skipping the plumbing-first approach is expensive. Really expensive.
The kitchen and bath industry generates over $235 billion in revenue and labor makes up 40-65% of the average remodel budget. So when pipes behind your beautiful new finishes start leaking you’re not just paying to fix the plumbing…
You’re paying to tear out and redo everything else too.
Common issues that pop up mid-renovation include:
- Old galvanised pipes that can’t handle modern water pressure
- Drains that don’t meet current slope requirements
- Missing or failed backflow prevention devices
- Vent stacks that were never properly installed
- Hidden leaks behind walls causing mould or rot
Each one of these is inexpensive to correct before tile installation. Each one is awful to correct after the tile goes up.
That’s why plumbing always has to be priority #1.
Backflow Testing: The Step Most Homeowners Miss
Backflow testing is the unsung hero of any plumbing inspection.
So what is it, exactly?
Backflow is caused by polluted water from sinks, sprinklers or the exterior entering your potable water system. This is typically due to a drastic shift in pressure — main break, fire in the area or municipal supply issue.
Backflow can send sewage, pesticides and chemicals into the pipes that supply your kitchen sink and bathroom faucets.
Pretty scary, right?
That’s exactly why backflow testing exists. A certified plumber will:
- Check the pressure on both sides of your backflow prevention device
- Confirm that check valves are sealing properly
- Replace any worn seals or failing parts
- Submit the test results to your local water authority
Here’s why this matters during a renovation…
When replacing fixtures, moving pipes, or adding new connections (i.e. fridge water line, pot filler, bidet, etc.), you may be introducing new cross-connection hazards. Backflow testing ensures these new connections will not contaminate your water.
Annual backflow testing is required by most municipalities for specific properties. Building or remodeling is a leading cause for needing another test. Neglecting to have it done can result in fines, failed inspections, and — in the worst case — drinking water full of contaminants for everyone in the home.
Plumbing Priorities For Kitchens
Kitchens have unique plumbing needs.
You have your main sink, dishwasher, fridge water line, sometimes a pot filler, sometimes a second prep sink. Each one of those requires an individual supply line, shut-off valve and drainage strategy.
Before renovating the kitchen, here’s the checklist:
- Supply line condition: Check old copper or galvanised lines and replace if corroded
- Sink slope: Drains, disposals, and dishwashers must be angled correctly for proper drainage
- Shut-off valves: Each appliance and fixture needs an accessible, working shut-off
- Garbage disposal setup: Often overlooked, often the first thing to fail
- Backflow prevention: Particularly if you have an outdoor garden faucet or pot filler hose connection
Do it correctly and your kitchen will function well for generations. Do it wrong and you will have leaks under your new cabinets in 1 year.
Plumbing Priorities For Bathrooms
Bathrooms are even more plumbing-heavy than kitchens.
A typical bathroom remodel ranges from $6,642 to $17,631 in 2025, with about half of that budget going towards labour costs. Plumbing fixtures account for one of the highest costs of any bathroom project due to each item requiring water supply, drainage, and venting.
Critical bathroom plumbing checks include:
- Toilet flange condition: Rotted flange equals leaking toilet (and ruined flooring underneath)
- Shower and tub drain placement: Once tile is set, these can’t move
- Hot water capacity: Rain showers and soaking tubs will use more hot water than your previous fixtures
- Vent stack location: Required by code and easy to forget
- Pipe size: Older homes may have undersized supply lines
Performing these tests first ensures that your bathroom will function correctly on day one AND ten years from now.
The Bottom Line
Kitchen and bathroom remodeling projects are typically the largest investments most homeowners will ever make. So how do you protect that investment? Here’s the simple answer:
Sort the plumbing first.
To quickly recap what to do before any tile, cabinet, or fixture goes in:
- Get a full plumbing inspection done by a licensed professional
- Schedule backflow testing and replace any failed devices
- Replace old supply lines and outdated drainage while the walls are open
- Plan fixture placement based on plumbing locations, not just looks
- Make sure permits and inspections are sorted before the renovation starts
If you don’t pay attention to these steps you will be part of the third of renovators who exceed their budget repairing errors that were preventable. Do them right and your renovation will look good, function flawlessly, and safeguard your water for decades.
Plumbing-first really is the only way to renovate properly.
