MDPE pipe and fittings are widely used for underground water supplies in domestic, agricultural, commercial and construction applications. Choosing the correct pipe size is important, but selecting the right fittings and installation components is equally essential.
At AJ Gammond, we supply a range of MDPE blue water pipe, MDPE fittings and associated products to help customers complete water supply installations.
This guide explains what MDPE pipe is, the different sizes available, the fittings you may need and what to consider before starting your installation.
What Is MDPE Pipe?
MDPE stands for Medium Density Polyethylene. MDPE pipe is a flexible plastic pipe commonly used for underground water supply systems.
Blue MDPE pipe is widely recognised for potable water applications and is available in different diameters and coil lengths.
Compared with rigid pipe systems, MDPE is flexible and can be supplied in long coils, which can make it particularly useful for longer underground installations.
Typical applications include:
- Domestic water supplies
- Agricultural water supplies
- Farm buildings
- Livestock water troughs
- Outbuildings
- Workshops
- New-build projects
- Groundworks
- Replacement water supplies
Always check that the pipe specification is suitable for the intended application.
Why Use MDPE Blue Water Pipe?
MDPE blue pipe is a popular choice for underground water supply installations because it offers several practical advantages.
Flexible
The flexibility of MDPE allows the pipe to follow the route of an installation without requiring a fitting at every change of direction.
Available in Long Coils
Long coils can reduce the number of joints required along an installation.
Durable
MDPE is designed for use in demanding underground applications when correctly selected and installed.
Easy to Handle
Compared with some rigid pipe materials, coiled MDPE can be relatively easy to transport and handle on site.
Suitable for Many Applications
MDPE can be used for a wide range of domestic, agricultural and building water supply applications, subject to the product specification.
What Size MDPE Pipe Do I Need?
Selecting the correct diameter is one of the most important decisions when purchasing MDPE pipe.
The required size can depend on:
- Required flow rate
- Length of the pipe run
- Available water pressure
- Number of outlets
- Property size
- Number of occupants
- Agricultural requirements
- Water trough requirements
- Installation design
Common MDPE pipe sizes include 20mm, 25mm, 32mm and larger diameters.
However, the largest pipe is not automatically the correct pipe.
The pipe should be sized according to the requirements of the complete water supply system.
If you’re unsure, speak to your plumber, installer or water professional before ordering.
MDPE Pipe Coil Lengths
MDPE water pipe is commonly supplied in long coils.
AJ Gammond supplies MDPE blue pipe in a range of lengths, including options such as:
- 25m
- 50m
- 100m
- 150m
Longer coils can be particularly useful for installations where a continuous run is required.
Before ordering, measure the proposed route carefully and allow additional length for connections and installation.
What Are MDPE Fittings?
MDPE fittings are used to connect MDPE pipe to other sections of pipe, valves, water supplies and equipment.
Compression fittings are commonly used because they allow MDPE pipe to be joined without specialist welding equipment.
Depending on your installation, you may require:
- Straight couplers
- Equal tees
- Reducing couplers
- Elbows
- Adaptors
- End caps
- Valves
- MDPE liners
Choosing fittings that match the pipe diameter is essential.
Philmac MDPE Fittings
Philmac fittings are widely used with MDPE pipe and provide a range of connection options for water supply installations.
AJ Gammond supplies a selection of Philmac MDPE products, making it possible to source pipe and associated fittings from the same supplier.
When selecting a fitting, check:
Pipe diameter → fitting size → connection type → application
This helps ensure you order the correct component for your installation.
MDPE Equal Tee
An equal tee allows a water supply to branch into two directions.
For example:
Main water supply
↓
Equal Tee
↙️ ↘️
Building Outbuilding
Equal tees are useful where the same pipe size needs to continue in multiple directions.
Always select a tee that matches the diameter of the MDPE pipe being installed.
MDPE Reducing Coupler
A reducing coupler allows two different pipe sizes to be connected.
This can be useful where an existing water supply needs to connect to a different diameter of MDPE pipe.
Before purchasing, check both pipe diameters to ensure the correct reducing coupler is selected.
MDPE End Caps
An end cap is used to terminate the end of a pipe.
End caps can be useful during installation where a pipe needs to be temporarily or permanently closed, subject to the application.
They can also be useful when extending or modifying an existing water supply system.
MDPE Pipe Liners
Pipe liners are an important component when using suitable compression fittings with MDPE pipe.
A liner provides internal support to the pipe where required by the fitting system.
For example, AJ Gammond supplies Philmac MDPE Liners for appropriate metric and imperial MDPE applications.
Always check the manufacturer’s instructions to establish whether a liner is required for the particular pipe and fitting combination.
MDPE Pipe Cutter
A clean, square pipe cut is important when installing compression fittings.
A suitable MDPE pipe cutter can help produce a clean cut and make installation easier.
Avoid cutting the pipe at an angle, as an uneven cut can affect the connection.
After cutting, check the pipe end for damage or deformation before installing the fitting.
How to Connect MDPE Pipe
The exact installation procedure depends on the fitting manufacturer, so always follow the manufacturer’s instructions.
A typical compression fitting installation involves:
1. Measure the pipe
Determine the required length before cutting.
2. Cut the pipe
Use a suitable pipe cutter and create a clean, square cut.
3. Prepare the pipe
Check the pipe end for damage and ensure it is clean.
4. Fit the required components
Install any required liner or other components according to the fitting manufacturer’s instructions.
5. Insert the pipe into the fitting
Push the pipe fully into the fitting as instructed by the manufacturer.
6. Tighten the fitting
Tighten according to the manufacturer’s instructions.
7. Test the installation
The completed installation should be tested appropriately before being put into service.
Always follow the fitting manufacturer’s installation instructions.
MDPE Pipe for Domestic Water Supplies
MDPE blue pipe is commonly used to connect properties to water supplies.
A domestic installation may involve a route from the water connection to:
- A house
- Garage
- Workshop
- Garden building
- Outbuilding
The required diameter will depend on the installation and water demand.
For new connections or replacement supplies, always check the requirements of the relevant water supplier.
MDPE Pipe for Agriculture
MDPE pipe is particularly useful in agricultural applications.
It can be used to supply water to:
- Livestock troughs
- Agricultural buildings
- Farms
- Workshops
- Outbuildings
- Remote water points
A typical agricultural installation could look like:
Water Supply
↓
MDPE Blue Pipe
↓
MDPE Tee
↙️ ↘️
Trough 1 Trough 2
This is where combining AJ Gammond’s MDPE pipe, fittings and water trough products can make it easier to source everything required for a project.
MDPE Pipe for Water Troughs
If you’re installing a new agricultural water trough, you may need more than just the trough itself.
A typical installation can require:
- Water trough
- MDPE blue pipe
- MDPE fittings
- Tee or elbow
- Valve
- Pipe clips or supports
- Appropriate connections
Planning the complete system before ordering can help ensure you have all the required components.
MDPE Pipe vs Barrier Pipe
Standard MDPE blue pipe is suitable for many water supply applications.
However, some sites may have ground contamination concerns where a specialist barrier pipe system may be more appropriate.
Barrier pipe is designed to provide additional protection against certain contaminants that could potentially affect a water supply.
The correct choice depends on the site and installation requirements.
If you’re unsure whether standard MDPE or barrier pipe is required, consult the relevant water professional or specification for the project.
How Much MDPE Pipe Do I Need?
Start by measuring the complete route.
Consider:
- Starting point
- End point
- Changes in direction
- Entry points into buildings
- Connection points
- Additional length required for installation
For example, if your measured route is 85 metres, a 100m coil may be more appropriate than joining several shorter lengths, depending on the installation.
Avoid ordering based solely on an approximate distance.
MDPE Pipe Fittings Buying Checklist
Before ordering, check:
- Pipe diameter
- Pipe length
- Pipe application
- Fitting manufacturer
- Fitting size
- Connection type
- Required tees
- Required bends
- Required couplers
- End caps
- Pipe liners
- Pipe cutter
- Valves
- Number of outlets
Planning the complete system can save time and prevent unnecessary additional orders.
Common MDPE Pipe Installation Mistakes
Choosing the wrong diameter
Don’t select pipe based purely on price or availability. The diameter should suit the requirements of the system.
Ordering the wrong fitting
Check the pipe diameter carefully before ordering fittings.
Forgetting liners
Some compression fitting systems require internal pipe liners. Always check the manufacturer’s requirements.
Cutting the pipe badly
Use an appropriate pipe cutter and make a clean, square cut.
Not planning the route
Measure the complete installation before purchasing pipe.
Mixing incompatible components
Ensure pipe and fittings are compatible and follow the manufacturer’s recommendations.
Frequently Asked Questions
What is MDPE pipe used for?
MDPE pipe is commonly used for underground water supply installations, including domestic, agricultural and building applications.
What colour is water supply MDPE pipe?
Blue MDPE is commonly used to identify potable water supply pipework.
What size MDPE pipe do I need?
The required size depends on factors such as flow rate, pipe length, water pressure and the number of outlets.
Can MDPE pipe be used underground?
Yes. MDPE is widely used for underground water supply installations when the correct product is selected and installed appropriately.
What are MDPE fittings?
MDPE fittings are components used to connect MDPE pipe to other pipework, valves, equipment or branches within a water supply system.
Do MDPE fittings require liners?
Some fitting systems require pipe liners to support the pipe when making a compression connection. Always follow the fitting manufacturer’s instructions.
Can I connect different sizes of MDPE pipe?
Yes, suitable reducing fittings can be used where compatible pipe sizes need to be connected.
How long does MDPE pipe last?
The service life depends on the product, installation conditions and application. Always refer to the manufacturer’s technical specifications.
Can MDPE pipe be used for agricultural water supplies?
MDPE is commonly used for agricultural water supply applications, including supplying livestock troughs and farm buildings, subject to the product specification.
Shop MDPE Pipe & Fittings at AJ Gammond
AJ Gammond supplies a range of MDPE blue water pipe, fittings and installation accessories for domestic, agricultural, building and groundworks applications:
Shop MDPE blue pipe in a range of diameters and coil lengths.
MDPE Fittings
Find compatible fittings for connecting and modifying MDPE water supply pipework.
Philmac Fittings
Browse Philmac products including tees, couplers, end caps and other MDPE connection components.
MDPE Liners
Find suitable pipe liners for compatible compression fitting applications.
MDPE Pipe Cutters
Use the appropriate cutting equipment to achieve a clean, square pipe end.
Water Troughs
For agricultural installations, combine MDPE pipe and fittings with a suitable water trough to create a complete water supply system.
Need Help Choosing MDPE Pipe & Fittings?
Choosing the correct pipe and fittings is important for any water supply installation.
Before ordering, make sure you know:
The pipe diameter + required length + fitting sizes + application + connection requirements.
If you’re unsure which MDPE pipe, fitting, liner or accessory you require, contact the AJ Gammond team before ordering.
AJ Gammond – supplying water pipe, drainage, agricultural, building, plumbing and trade products across the UK.