Replacing Outdoor Water Pipes: A Guide by DHC Utilities

Outdoor water pipes are a vital part of a property's infrastructure, but over time, they can become corroded, damaged, or outdated, resulting in reduced water pressure, leaks, or health hazards such as lead contamination. At DHC Utilities, we specialise in replacing outdoor water pipes using the most efficient, least disruptive methods available, ensuring your water supply remains clean, reliable, and safe.

In this guide, we cover everything you need to know about replacing outdoor water pipes, from the reasons you might need to do so to the methods, costs, legal responsibilities, and more.

Why Replace Your Outdoor Water Pipes?

There are several reasons why homeowners or businesses consider replacing their outdoor water pipes. In many cases, it is not just about fixing a problem—it’s about future-proofing the property and ensuring compliance with modern standards.

Common Reasons Include:

• Ageing Infrastructure: Older pipes, particularly those made from lead or galvanised iron, degrade over time and are more prone to failure.

• Leaks and Water Damage: Cracked or burst pipes can lead to extensive water damage, structural issues, and increased utility bills.

• Low Water Pressure: Narrow, scaled, or damaged pipes can restrict water flow, impacting the effectiveness of taps, showers, and appliances.

• Health Risks from Lead Pipes: Lead contamination poses serious health risks, especially to children and pregnant women.

• Property Renovations: Moving or extending a property often requires repositioning the main water supply pipe.

• Switching from Shared Supply: Many older homes share a supply pipe with neighbouring properties. Upgrading to an independent supply improves pressure and accountability.

Who Is Responsible for Outdoor Water Pipes?

Understanding your responsibilities versus those of your water company is essential before commencing any work.

Your Responsibility

You are responsible for:

• Internal plumbing (everything inside your property)

• The supply pipe: this runs from your external stop tap (typically at your boundary) into your home

If you share a supply pipe with neighbours, you are each responsible for the branch that serves your own property.

The Water Company’s Responsibility

Your water supplier is responsible for the communication pipe. This runs from the water main in the road up to your external stop tap

If replacement work is needed beyond your boundary or involves the communication pipe, it may be eligible for support from the water company, especially if you’re replacing lead or iron pipes.

Replacement Methods: Trenching vs. Moling

At DHC Utilities, we offer two main options for outdoor pipe replacement: traditional trenching and modern trenchless moling. The choice depends on your property layout, soil type, and level of disruption you can tolerate.

1. Traditional Trenching

Traditional trenching is the most common method for replacing outdoor water pipes. It involves digging a continuous trench along the existing pipe's route, from the outside stop valve at the property boundary to the point where the pipe enters your home. This approach offers full visibility of the pipework, allowing engineers to inspect the route and install the new pipe in a controlled, precise manner.

The process begins with marking out the proposed route and excavating to the required depth, typically between 750mm and 1350mm, in accordance with UK water regulations. Once exposed, the old pipe is either removed or capped off, and a new 25mm MDPE (medium-density polyethene) pipe is laid securely in its place. To protect the pipe and ensure compliance, soft sand is laid around it before the trench is carefully backfilled and compacted. Any disturbed surfaces — whether turf, gravel, tarmac, or paving — are then reinstated.

This method is particularly suitable where the pipe route is straightforward, and surface materials can be easily restored. It's often chosen for properties undergoing major landscaping or renovation, where surface disruption is less of a concern. It’s also appropriate when trenchless techniques such as moling aren’t feasible — for instance, in areas with tight access, complex underground services, or highly compacted ground.

However, trenching does come with its drawbacks. It can be significantly more disruptive than trenchless methods, especially where the route crosses driveways, patios, or landscaped gardens. It’s also more labour-intensive, often requiring a longer timescale to complete due to the excavation, pipe laying, and reinstatement phases. If the trench extends onto public land, permits and traffic management plans may also be required — something we handle in full at DHC Utilities.

2. Trenchless Moling

Trenchless moling is a modern, highly efficient method of installing new water supply pipes with minimal disruption to the surface above. Instead of excavating a continuous trench, this technique uses a pneumatic tool known as a ‘mole’, which burrows underground to create a path for the new pipe. The mole travels between two small excavations — a launch pit at one end and a reception pit at the other — effectively tunnelling beneath lawns, driveways, patios, or other obstructions without disturbing the surface.

This approach is particularly well-suited to residential properties where preserving the condition of outdoor areas is a priority. It is ideal for pipe routes that run under landscaped gardens, block-paved driveways, or through areas with limited access. Because only small pits are required at either end of the pipe route, moling significantly reduces the amount of excavation, mess, and reinstatement work involved.

One of the key advantages of moling is its speed. With fewer materials to remove and reinstate, the installation process can often be completed more quickly than traditional trenching. It is also less labour-intensive, making it more cost-effective for many domestic applications.

At DHC Utilities, we use trenchless moling wherever possible. Our team assesses each site on a case-by-case basis to determine the most appropriate method of installation. Where moling is feasible, we aim to minimise surface disruption, reduce labour costs, and complete the replacement quickly—all while ensuring the highest standards of workmanship and compliance.

Lead Pipe Replacement Schemes

If your property was built before 1970, there’s a chance it still contains lead pipework. Replacing these pipes is strongly recommended — and in some cases, your water company may contribute to or fully cover the cost of replacing the communication pipe.

Health Risks of Lead Pipes

Lead pipes pose a significant health risk because over time, lead can leach into drinking water, especially if the water is soft or has been sitting in the pipes for an extended period. Consuming even small amounts of lead over a long period can lead to serious health complications. These risks include elevated blood pressure, kidney damage, and developmental issues in children, such as learning difficulties and behavioural problems. Pregnant women are particularly vulnerable, as lead exposure can increase the risk of miscarriage and cause harm to the developing fetus. Given these dangers, replacing lead pipework is a crucial step in safeguarding household health and ensuring a safe, clean water supply.

Support Available:

Water companies such as Thames Water and United Utilities offer Lead Pipe Replacement Schemes, which may include:

• Free like-for-like replacement of the communication pipe

• Support with reconnection following private works

• Guidelines for trench depth, pipe specifications, and inspection

To qualify, you usually need to:

• Replace your side of the pipework within 3 months

• Use 25mm MDPE (or match existing diameter)

• Comply with trench depth (typically 750–1350mm)

• Use an approved plumber (or have the trench inspected)

We can advise and assist you through this process, helping with applications and ensuring your installation meets all water authority requirements.

Step-by-Step: Replacing Your Outdoor Water Pipe

Replacing a supply pipe might sound daunting, but with a structured approach, it can be efficient and stress-free. Here’s how we handle the process at DHC Utilities:

1. Initial Survey and Pipe Identification

We begin with a site visit to inspect your current pipework, determine whether you have lead or galvanised pipes, and identify the route of the existing supply.

2. Quote and Proposal

Based on the findings, we provide a no-obligation quote. We also advise on the most suitable method — moling or trenching — and outline any additional work or requirements (e.g. moving stop taps).

3. Application Support (if needed)

If your water company offers a replacement scheme, we will help with your application and liaise with them directly to coordinate work.

4. Installation

• Small pits or trenches are excavated (as required)

• New pipe (usually 25mm MDPE) is laid via moling or trenching

• Pressure testing is performed to ensure there are no leaks

• Connections are made to internal plumbing

5. Reinstatement

We restore any disturbed ground, whether it’s turf, paving, or tarmac, leaving the site neat and tidy.

6. Certification and Handover

We issue any relevant documentation and, if applicable, provide evidence for the water company to proceed with their part of the replacement.

Can I Replace the Pipe Myself?

While it’s technically possible for a competent DIYer to lay a new supply pipe, we strongly recommend against it. There are several reasons why:

• Compliance with Water Supply (Water Fittings) Regulations 1999

• Avoiding cross-contamination of drinking water

• Meeting trench depth and installation standards

• Ensuring safe electrical earthing if lead is replaced

• Speed and efficiency of experienced teams

Only WIAPS or WaterSafe-approved plumbers can certify works without inspection, saving time and hassle. At DHC Utilities, we are fully accredited and handle both the practical and administrative side of the process.

Frequently Asked Questions

How long does it take to replace outdoor water pipes?

Most domestic supply replacements take half a day to two days, depending on the length and method. Moling is usually faster and less invasive.

Do I need permission from the council?

If work involves a public highway or pavement, a permit and traffic management may be required. We manage this as part of our service.

Will the water be off during the work?

Yes, but only temporarily — usually for a few hours while we make the switch. We’ll inform you in advance and schedule work at a convenient time.

Will my insurance cover this?

Some building's insurance policies cover accidental pipe damage but may not cover upgrades. It’s best to check your policy in advance.

Are shared supplies still legal?

Yes, but they’re outdated. Switching to an independent supply improves flow, ownership clarity, and reliability. We can assess whether you’re on a shared connection.

Why Choose DHC Utilities?

At DHC Utilities, we combine years of experience with the latest trenchless technology to offer a fast, tidy and professional service. Whether you’re upgrading old lead pipes, fixing a leak, or installing a new supply for an extension, we’re here to help every step of the way.

Our team is:

• WaterSafe and WIAPS-certified

• Available for emergency callouts and planned works

• Committed to customer satisfaction and minimal disruption

• Trusted by homeowners, landlords, and developers across the UK

Ready to Replace Your Outdoor Water Pipe?

If you’re concerned about ageing or faulty water pipes, or simply want to upgrade to a more efficient system, get in touch with us today. We’ll arrange a free consultation and provide expert advice tailored to your property.

Contact DHC Utilities to get started — we’re here to make your water supply safer, stronger, and future-ready.