MDPE Water Pipe Fittings Explained: A Beginner's Guide

Whether you're installing a new water supply to a livestock trough, replacing old pipework or extending a water system around the farm, choosing the correct MDPE water pipe fittings is essential. With so many different couplings, elbows and tees available, it can be difficult to know which fitting you need.

This beginner's guide explains the most common MDPE pipe fittings, what they do and how to choose the right one for your project.

What Is MDPE Pipe?

MDPE (Medium Density Polyethylene) pipe is the standard choice for underground cold water systems throughout the UK. It is lightweight, durable, corrosion-resistant and easy to install, making it ideal for agricultural, equestrian, domestic and commercial water supplies.

MDPE pipe is commonly used for:

• Livestock water systems
• Drinking water supplies
• Field trough installations
• Garden irrigation
• Yard and farm water distribution
• New property water connections

Choosing the Correct Pipe Size

The most common MDPE pipe sizes are:

• 20mm – Small domestic water supplies and short pipe runs.
• 25mm – The most popular size for farms, gardens and general water distribution.
• 32mm – Larger water demands, multiple troughs and longer distances.
• 40mm, 50mm and above – Commercial and high-flow applications.

Always check the outside diameter of your existing pipe before ordering fittings, as MDPE fittings are sized to match the pipe's external diameter.

Compression Fittings Explained

Most MDPE fittings use a compression design. This means the pipe is pushed into the fitting and tightened using a nut, creating a watertight seal without the need for glue or specialist equipment.

Compression fittings are:

• Quick to install
• Reusable in many cases
• Strong and reliable
• Suitable for underground use
• Easy to maintain

Many quality fittings, including those from Plasson, are WRAS approved for drinking water applications.

The Most Common MDPE Pipe Fittings

Straight Couplings

Straight couplings join two pieces of the same size MDPE pipe together.

Typical uses include:

• Repairing damaged pipe
• Extending an existing pipeline
• Joining new sections of pipe

Reducing Couplings

Reducing couplings join pipes of different sizes.

For example:

• 32mm to 25mm
• 25mm to 20mm

These are useful when connecting new pipework to an existing installation.

Elbows

Elbows allow the pipe to change direction, usually by 90°.

Ideal for:

• Water troughs
• Building corners
• Water tanks
• Pump connections

Using an elbow instead of bending the pipe too sharply helps maintain water flow and reduces stress on the pipe.

Tees

A tee fitting splits one pipeline into two.

Common applications include:

• Feeding multiple livestock troughs
• Running water to several fields
• Branching off to buildings or yards

Tees make expanding an existing water system simple and efficient.

End Caps (Bungs)

An end cap or bung seals the end of an MDPE pipeline.

These are useful when:

• Pressure testing a new system
• Temporarily closing a pipeline
• Allowing for future expansion

Male Threaded Adaptors

Male adaptors connect MDPE pipe to fittings with a female threaded connection.

Typical connections include:

• Ball valves
• Stop taps
• Pumps
• Water filters
• Trough valves

Female Threaded Adaptors

Female adaptors connect MDPE pipe to components with a male threaded connection.

These are commonly used when connecting to:

• Brass fittings
• Tap connectors
• Water tanks
• Irrigation equipment

Wall Plate Elbows

Wall plate elbows provide a secure fixing point where a tap or valve needs to be mounted onto a wall or timber post.

They are commonly used for:

• Yard taps
• Wash-down areas
• Stable blocks
• Workshops

Why Choose Plasson MDPE Fittings?

Plasson fittings have become one of the most trusted names in agricultural and water supply installations.

They are known for:

• Excellent build quality
• Reliable leak-free performance
• Easy installation
• Long service life
• UV-resistant materials
• WRAS approval on many products

For farms where reliability matters, investing in quality fittings can save both time and future repair costs.

Installation Tips

For the best results:

• Cut the pipe square using a suitable pipe cutter.
• Remove any burrs from the cut edge.
• Mark the insertion depth before fitting.
• Push the pipe fully into the fitting.
• Tighten the compression nut according to the manufacturer's guidance.
• Pressure test the system before backfilling trenches.

Taking a little extra care during installation can help prevent leaks and ensure a long-lasting water system.

Common Questions

Can MDPE fittings be buried underground?

Yes. Compression MDPE fittings are designed for underground use when installed correctly.

Do I need PTFE tape?

Only on threaded connections. Compression joints themselves do not require PTFE tape.

Can I reuse MDPE fittings?

In many cases, yes, provided the fitting is undamaged and the sealing components remain in good condition.

Are MDPE fittings suitable for drinking water?

Many quality fittings are WRAS approved and suitable for potable water supplies. Always check the product specification before installation.

Shop MDPE Water Pipe Fittings Online

At Skipton Dairy Services, we stock a wide range of Plasson MDPE pipe fittings, including:

• Straight couplings
• Reducing couplings
• Elbows
• Tees
• End caps
• Male threaded adaptors
• Female threaded adaptors
• Wall plate elbows
• Brass bib taps and accessories

Whether you're installing a single livestock trough or a complete farm water system, we're here to help you choose the right fittings.