Burst Main or Blocked Drain Farnborough | How to Tell

Water where it shouldn't be is always unsettling. You step outside your shop on Queensmead, or you're walking to the car on a residential street just off the town centre, and there's a wet patch spreading across the pavement. Or maybe your kitchen drain has gone sluggish and there's a damp smell you can't place. The question that immediately matters is: is this a burst supply pipe, or is this a drainage problem?

They look similar on the surface. Both can cause pooling water, damp walls, and that general sense that something underground has gone wrong. But they're completely different problems, they need completely different responses, and you'd call completely different people. Getting that wrong wastes time and, in a burst main situation, can mean water damage keeps spreading while you wait for the wrong tradesperson to show up.

Let me walk you through the differences.

What You're Actually Looking At

Your property has two separate water systems running underground. The supply side brings clean, pressurised water in from the mains. The drainage side takes wastewater away. A fault on either one can produce visible water at ground level, but the behaviour of that water tells you which system has failed.

Signs you're dealing with a burst or leaking supply pipe

• Water is clean and clear, not discoloured or smelly
• It keeps coming. Supply pipes are pressurised, so if one bursts, water keeps flowing until someone isolates it
• The wet patch grows steadily even when no one in the building is running taps or flushing toilets
• You may hear a faint hissing sound from beneath the ground
• Your water pressure inside drops noticeably, or taps run slower than usual
• In some cases, the ground bubbles or water rises up through cracks in paving

In Farnborough town centre, the streets around Meudon Avenue, Victoria Road and Prospect Road have a mix of older mains infrastructure and more recently laid pipes, so bursts do happen, particularly after a dry spell followed by heavy rain when ground movement puts stress on older joints.

Signs you're dealing with a drainage problem

• Water or liquid has a smell, anywhere from musty to actively sewage-like
• Pooling tends to appear after rain or after the building has been in use, not continuously
• Internal drains are slow or completely blocked
• Manholes nearby are surcharging, meaning water is backing up and coming out of the top
• Damp is appearing on walls at low level inside, often with a grey-brown staining
• Toilets are gurgling even when you haven't flushed them recently

A blocked or collapsed drain doesn't have the same constant pressure behind it. The wet patch grows when the drain is under load and eases off when it isn't, usually.

A Quick Side-by-Side

Who Owns the Problem

This is where people get confused, and I don't blame them. The rule of thumb is this:

If the burst is in the public water main, that belongs to South East Water and they fix it at no cost to you. Call them straight away on 0333 000 0002. They have an emergency line and they will send someone.

If the burst is in the supply pipe between the public main and your property boundary, that's yours. It's private pipework and you'll need a plumber or your water company may have a homecare plan that covers it.

For drainage, the split is similar. Public sewers, the ones shared between properties, are managed by Thames Water. But your private drain, the one that runs from your building to the shared sewer, is your responsibility. That's where Drainsco comes in.

So if your drain is blocked, collapsed, or leaking on your side of the boundary, you don't need to call Thames Water first. Call a drainage engineer. We can get there faster, we can CCTV the drain to see exactly what's happening, and we can clear it, repair it, or reline it depending on what we find.

The Job That Prompted This Post

A few months ago I took a call from a business owner on Lynchford Road, just on the edge of the town centre. He'd come in on a Monday morning to find a wet patch spreading across the car park at the rear of the building. His first instinct was burst water main, so he'd called South East Water the Friday before and they'd done a site visit and found nothing on their side.

By the time I arrived, the wet patch was bigger and there was a faint smell, not strong, but it was there. I lifted the inspection chamber at the back of the building and found it surcharging. Root ingress, as it turned out, a large tree in a neighbouring garden had sent roots through a clay junction about four metres from the chamber. The blockage was causing water to back up and find its way out through a crack in the chamber wall.

We water-jetted the roots clear, ran a CCTV survey to see the full extent of the damage, and came back two days later to reline the affected section. The ground dried out within a week. The business owner told me he'd nearly spent the weekend digging up the car park himself because he thought it was a burst pipe. It wasn't. The smell, the link to building use, and the surcharging chamber were the clues.

If You're Still Not Sure

That's genuinely fine. It's not always obvious, especially if you can't access your manhole covers or you're not confident reading what you see. A few quick checks:

1. Turn off everything in the building that uses water, every tap, the washing machine, the dishwasher. If the wet patch keeps growing, that points strongly toward a supply issue. If it stops growing, the drainage system is more likely involved.
2. Check the meter. Most Farnborough properties have a stop tap and sometimes a meter near the boundary. If the meter is still running with everything turned off inside, water is escaping from your supply pipework.
3. Have a look at the nearest manhole or gully. Is water sitting in or around it? That's a drainage tell.

If the meter's spinning with everything off, call South East Water. If the manhole's surcharging or the drains inside the building are misbehaving, call a drainage engineer.

Drainsco covers Farnborough and across the GU postcodes, with engineers on call around the clock. There's no call-out fee, and you'll get a clear price before any work starts. If you're not certain which problem you've got, give us a call anyway. We'll ask you the right questions over the phone and point you in the right direction, even if that direction turns out to be the water company.