Informational Guide

How To Correctly Plumb A House

In this guide, we cover everything you need to know for how to plumb a house, including all the pipes, fixtures, connections, tools & more.

by Ian Haynes

DIYers understand the genuine satisfaction you can get from building or installing something yourself. There are now more guides, resources, and information available than ever before, so more people than ever are taking on the challenge of doing it themselves without professional assistance.  

For homeowners, plumbing has often seemed like something they couldn’t do themselves, but this isn't the case. DIY plumbing is a lot more affordable and can actually be a lot quicker than hiring a professional 

This guide will give you everything you need to know to properly plumb a house, including all the pipes, fixtures, and connections.  

How To Plumb A House

Plumbing is one of those things we take for granted every day, but it is a reasonably new invention in the grand scheme of things. While the Romans understood the value of a good home plumbing system, it’s only in the past 100 years or so we've got to the stage of having really efficient plumbing 

Having a really good plumbing system is important for a number of key reasons: 

  • Use Of Safe And Clean Water Resources 
    Health and hygiene rely on having a safe, clean water source. Your plumbing system does all of this without you having to even leave the house.  
  • Reduces Consumption 
    Believe it or not, plumbing is actually more environmentally friendly because it limits your water usage. An efficient plumbing system helps you use water more effectively, so you only use what you need. This is good for the planet and helps keep bills down.  
  • Comfort 
    Home plumbing is the ultimate luxury. It gives us access to basically everything we need without any fuss, hassle, or stress. With everything going on in the world, it’s comforting to know the essentials are there.   
  • Prevents Rot And Mold 
    Poor plumbing allows dampness into your home, which can damage your property and even impact your health. A good, reliable home plumbing system helps prevent any leaks and stops rot and mold damage before it starts. 
  • Hygiene 
    Home plumbing systems really came about to help improve overall hygiene. A good, functioning plumbing system safely gets rid of all your waste, keeping you and your home hygienic and clean.  

Main Components Of Your Home’s Plumbing System  

Before you can plumb a house, you need to understand it. Here are the key components that you should familiarize yourself with:  

Pipes 

Pipes are used to allow clean water to flow in and to drain wastewater (often containing sewage) out of your home. Water coming into your home is pressurized, typically 50-60 psibut outgoing water isn’t, which is why drainpipes need to be at a downward angle. Ventilation going through your pipes helps ensure that there are no blockages.  

Plumbing Fixtures 

Your plumbing fixtures are what you will attach the supply lines and drainage lines to. In your bathroom, this is typically your shower, your bathtub, your sink, and your home toilet 

Septic Tanks And Sewer Lines 

Septic tanks separate solid and liquid waste. Solid waste is then broken down, typically using microorganisms, and then it is all emptied through your pipes into the sewage lines.  

Water Supply System 

Your water supply system is how clean water coming into your home will be distributed. This all comes from a single supply line underneath your home and will then be directed in two directions. It will either come through as a clean cold-water supply or go through your water heater/boiler to be used as hot water. Smaller supply lines will run to each fixture in your home.  

Drain System 

Your drain system is the network of pipes that will carry wastewater from each fixture into your main drainpipe underneath your house. Your drainage system will need to be fitted first and will, in some cases, need to be installed before your floor can be concreted.  


Considerations When Plumbing Your House 

There are normally a few options when it comes to plumbing your house, and the choice you make will be determined by your circumstances. Here are some of the key considerations to take into account: 

  • Corrosive Water 
    Corrosive water is usually caused by the environmental conditions around your house and the different elements in your water supply. Corrosive water can be really damaging to metal water systems, so you may want to consider PEX piping which is much more resistant.  
  • Water Pressure 
    Your water pressure influences how well your fixtures will operate. You want plumbing that can handle higher pressure, and plastic pipes are well suited for this.  
  • Water Flow 
    The effectiveness of your plumbing is determined by the flow of the water in and out of your house. Smoother pipes allow the water to flow more efficiently, and brass has been found to remove almost all friction for an effortless flow.  
  • Characteristics Of Soil
    The soil around your home is likely to impact your pipes. Some soil can infiltrate your pipes over time and impact the quality of your water supply. If you have specific types of soil or rock in your area, you may need specialist pipes.  
  • Heat & Temperature 
    Some types of pipes are not well suited for high or low temperatures. If you live in a cold climate, you need pipes that are insulated against freezing. You’ll also need your hot water supply pipes to be heat resistant so they don’t get damaged.  
  • Characteristics Of Material 
    The type of material you use for your pipes will have a noticeable impact on your plumbing system. Metals are often effective for a good flow and can take a great deal of stress, but plastic PEX pipes are a lot more flexible. You should choose a material which fits your individual needs.  

How To Plumb A House (Step-By-Step Instructions)  

To plumb a house, you’ll need a range of different materials and tools. This list isn’t definitive, but you should make sure you have every item before you start work: 

  • Protective equipment (gloves and goggles/eye protection at a minimum) 
  • Pipe cutters 
  • Pliers 
  • Wrench  
  • Screwdrivers 
  • Saw/hacksaw 
  • Spirit level 
  • Tape measure 
  • Pipes 
  • Plumbers putty 
  • Nuts and bolts (as needed for each piece of equipment) 
  • Caulk  
  • Rags, towels or old clothes 

Once you have all your equipment, you should follow these steps: 

Plumbing A House  

  • 1
    Plan your layout 
    When you’re plumbing a new house, you need to plan it out carefully. Every single fixture that needs water needs to be accounted for because they will need to be connected to your drainage systems. Before you do anything else, make sure you have it all drawn out.  
How To Plumb A House Basics
  • 2
    Install the sewer drains 
    Sewer drain stubs are what all your drains will connect to. These need to be installed before the concrete in the foundation is laid, so it’s important to do this before anything else. If your concrete, it becomes a lot more complicated because you’ll need to drill through it.  
  • 3
    Drainage stacks and toilet flanges 
    You now need to install your drainage stacks and other essential fittings such as toilet flanges. Drainage stacks are used to centralize all your drains, so they flow to one point and then out of your house. Ensure these are located where all your fittings can reach and deep enough that there’s a downward slope. Now, make sure your toilet drains are fitted. These are generally directly into the floor, and you’ll need to sort this before your toilet can be installed.  
How To Install Plumbing For A New House
  • 4
    Fit your supply line  
    Now your drainage systems have some roots, you need to sort the supply lines. Your pressurized supply line will run underneath your house and then split into two, a hot water supply that connects to your water heater and your cold-water supply. From there, the water supply is carried by smaller pipes to each fixture. The majority of your fixtures will need hot and cold water (your toilet won’t), so you need to fit these smaller supply lines so that they reach the planned location of each fitting.  
  • 5
    Rough-in 
    An important next step is the rough-in. You need to lift all your fixtures (sinks, bathtubs, toilets) into place and make sure they all fit. Don’t connect anything yet. Just measure it out and make sure you have enough room. If it doesn’t, then you need to consider the layout or the positioning of your walls. Once you’re happy with the location, you can fix all your walls and doorways into place.  
  • 6
    Install the fixtures 
    Now your walls are all established and you have drains and laid pipe going to each fixture location, you need to install your sinks, bathtubs, toilets, and any other devices which require a water supply. The exact method will vary for each of these, but further down in this article, we have guides for each. Make sure you tighten all water supply pipes using nuts, bolts, and your wrench, and make sure that your supply lines can reach your fixtures.  
  • 7
    Install your traps 
    This is part of the previous step, but it’s worth calling out. Every plumbed fixture will need an S, P or U trap underneath it. These function to keep bad odors from rising out of your drain and keep your drains running efficiently. These are part of the plumbing for each device and are usually located pretty close to the water drain. 
  • 8
    Ventilation 
    Finally, you need to install the ventilation. Every plumbed device needs ventilation because it allows air into the drainage system and balances your water pressure. Without this, your drains won't flow, and sewage won't be passed out of your house. To make life easier, you can fit a single ventilation pipe to your sink and connect it to other fixtures, but always remember your vent needs to be higher than any drains on fixtures.  
How To Plumb A House With PEX

Plumbing A House Using PEX 

PEX is a modern alternative to traditional pipes, which offers a number of benefits. It’s flexible, adaptable, and affordable, plus it's easy for DIYers to use. 

PEX is only really suitable for water supply pipes (water coming into your home), so you’ll generally want to use PVC for the drain lines. This is purely because PVC is more solid and can handle the heavy flow of water and sewage your drain will have to deal with.  

To plumb your house using PEX, you’ll need to follow the steps above with a few exceptions.  

  • 1
    Install The PVC Drain Pipes 
    When laying your pipe, you'll want to use PVC rather than traditional copper or metal. These should still be 3-4 inches thick with smaller drains to go to each fixture.  
  • 2
    Measure The Supply Line 
    PEX is incredibly versatile but needs to be cut to the right length with PEX pipe cutters. When planning out your house, you’ll need to measure how much pipe needs to be laid to get to each fixture and trim it appropriately.  
  • 3
    Colour Code The Supply Lines 
    PEX is available in a range of colors, and it’s a good idea to color-code your supply lines when plumbing each fixture. Using red for hot and blue for cold makes it a lot easier in the long run if you need to do any repairs or make any changes. 
How To Plumb A House Using PEX
  • 4
    Use A Crimping Tool  
    Connecting PEX pipes is very easy compared to copper, and no soldering is required. You will need to get your hands on a specific crimping tool, though. The crimping method essentially molds the PEX pipe into a metal ring at the end, which is secured in place using the crimping tool. Use this when installing your fixtures.  

Plumbing In A Tiny House 

If you have a tiny house or mobile home, you have a few different options for plumbing. You need to separate the drainage and supply options and consider them separately in this instance:  

  • 1
    Grid Drainage  
    The most commonly used method for tiny houses is to connect your drains to the grid or public sewage system. To do this, you follow the standard steps that any homeowner needs to take.  
  • 2
    Sanitary Tank  
    Alternatively, you can fit the drainage system the same way but connect it to a sanitary tank. This will store your sewage which will need to be emptied periodically so it can continue to be used. 

Once you’ve decided on your drainage, you can consider your supply: 

  • 1
    Hook-Up Method 
    In the hook-up method, you hook up your pipes to a very limited water supply like a hose. This uses much thinner supply pipes than usual, typically only 1 inch in diameter, and pressurizes the water so it can be used in your home. This is not a very effective way of distributing water in your house, but it is pretty simple. 
  • 2
    Tank And Pump 
    Alternatively, you can have your pipes installed throughout your tiny house and use a pump to get it into all the viable rooms. The water is stored in the tank, and an electric pump is used for this. If your house is really tiny, this can be quite effective and economical.  
  • 3
    Traditional Supply Lines 
    If you live in an urban setting, you should have access to the supply lines which run under the ground. You can tap into these like any other house and use them to distribute the water around your home. This is definitely the method we’d recommend.  

How To Plan The Plumbing Layout For A New Home 

Your plumbing layout is the plan of all the different pipes, fittings, connections, and fixtures you want to go into your home. It’s absolutely vital you think this all through beforehand because it will determine what work you undertake, the materials you need, and even some of the construction elements.  

You’ll need to follow these steps to create an effective plumbing layout: 

1. Use A key  

To save you sketching out every fitting and connection, it’s usually fairly standard to have a key. The image below is what’s commonly used, but if it's only for you, then you can mark your layout however you like.  

How To Layout Plumbing For A New House

2. Map your existing plumbing 

If you have plumbing in your home already, you must draw it out as it is now. The location of different pipes and holes will influence your new layout. 

3. Measure up 

Measure all the different fixtures, pipes, and drains you’ll be using for the work. These will often be labeled anyway, but you need to have them accurately for your plumbing layout.  

4. Map your drainage 

Start by drawing your drain lines in. If you have a basement, this should be at least 1 foot below the floor and sloping downwards to encourage sewage to flow. If you don’t have a basement, then this should still slope, but it may be nearer to the surface. Draw out all your drain lines so you can start to see how they will fit together.  

5. Map your supply lines 

You should have a supply line running beneath your house. Put this in the layout because supply lines will have to originate here.  

6. Draw your fixtures 

Put your fixtures (sinks, bathtubs, toilets, etc.) in the plumbing layout so you can clearly see where they’ll go.  

7. Map the pipes 

Now you have your fixtures, drain, and supply lines mapped, you need to work out how the pipes will reach each fixture. The majority of your pipes will go through your walls or floorboards, and this plumbing layout will help determine where you need to create holes.  

8. Draw the ventilation 

Finally, map out where your ventilation will go. This needs to be higher than your drains, and you may choose to have this going out from the roof of your house.  

When you've followed all these steps, you'll have a drawing that looks a bit like the one below. This can then be used so you can create your rough-in. 

How To Plan Plumbing Vents

Home Plumbing Costs (Can You Plumb Your Own House?) 

Cost To Replace All Plumbing In A home

Replacing the entire plumbing in your home is a big task and won’t be cheap. It will typically cost $5000-$15,000, depending on the size of your home. If you choose to do it yourself and only buy parts, it should be under $10,000. Remember to factor in the time you’ll take to do it because time is money. You will also probably need to acquire specialized permits, depending on where you live.  

Cost Rough Plumb A House 

To rough plumb a house will cost between $500 and $1500 per fixture. This includes the parts and labor of a professional, but if you choose to do it yourself, then it will typically be $200-$1000, depending on the fixture.  

Cost To Install Plumbing In A House 

Installing plumbing in a new house is made more complicated because you don’t have the drains, etc., established. This will usually cost you $15,000-$25,000, depending on your area. If you choose to do this yourself, it will likely cost you $10,000-$15,000, but you may need to get a professional to look over the work.  

With all plumbing work, you should consider your materials and your labor costs. By using PEX instead of metal, you can save up to 40% of the overall cost, and by doing it yourself, you can reduce the costs even further. As a general rule of thumb, it will cost about $5 per square foot to plumb your house.  

How To Guide - Home Plumbing in 2021 

Plumbing is not a one size fits all job, and you need to consider every situation, and component, separately.

We have created a range of plumbing guides that give you step-by-step instructions on how to plumb individual fixtures correctly. We’ve also created bespoke guides on the following topics: 


People also Ask (FAQs)

Do water pipes run through walls? 

Yes, and it’s essential to know where they're located if you're having any building work done.  

How much does it cost to plumb a 1500 sq ft house? 

It will cost roughly $2000-$4000 to plumb a 1500 sq ft house yourself, or $5000-$8000 to hire a professional.  

Where does the main water line enter a house? 

Your main water line enters your house at ground level. If you have a basement, it will usually be down there on the floor.  

How long does it take to plumb a new house? 

It will typically take 5-7 days to plumb a new house. It may take longer if you’re doing it yourself.  

How do you winterize a homes plumbing system? 

To help stop your pipes from freezing, you should insulate them and run the water regularly. We have a full step-by-step guide that can be found here 


Conclusion

When you think about plumbing a whole house, you might be intimidated. It is a lot of work, but it is totally doable. We’ve given you everything you need, and hopefully this guide has given you the confidence to get started yourself.

Take it step by step and one fixture at a time and you should be fine, but always remember to get a professional plumber involved if you're worried.  

Ian Haynes is an expert writer who has successfully deployed over 500 plumbing pages and other related content. He has an excellent understanding of home plumbing issues and translates his experiences via Plumbing Lab so readers can have a better understanding of common household problems. Outside of his work, Ian likes exploring Brooklyn with his Labrador.

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