A drain that keeps blocking has an underlying cause that a quick unblock does not fix, usually a build-up of fat or wipes, tree roots getting in through the joints, a cracked or displaced pipe, or a dip where waste settles. To stop it for good, the drain needs to be cleaned fully with a high-pressure jetter, checked with a CCTV camera to find the cause, and then repaired, which is what an experienced drainage engineer in St Albans or anywhere else should do rather than just clearing it again.

Why a drain blocks more than once

When a drain is cleared with rods, the rod punches through the blockage and the water drains away. That fixes the symptom, but it often leaves fat coating the pipe walls, a root mass still growing through a joint, or a cracked section still catching debris. Within weeks or months, waste builds up on the same spot and the drain blocks again.

A repeat blockage is a clue. It tells you there is something about that pipe, or about what goes down it, that keeps catching waste. Finding it is the whole job.

The common causes of repeat blockages

Cause	What you might notice	How it is found	The lasting fix
Fat, oil and grease build-up	Kitchen sink and gully slow first, blocks every few months	CCTV shows a thick coating narrowing the pipe	Jetting to clear the coating, then keep fat out of the sink
Wet wipes and sanitary products	Toilet or main drain blocks, often with paper mixed in	Visible in the chamber or on camera	Bin all wipes, even those labelled flushable
Tree and shrub roots	Repeat blockages at the same point, often worse in dry summers	CCTV shows roots through joints	Root cutting, then patch lining or relining to seal the joints
Cracked or broken pipe	Blockages, smells, sometimes damp or subsidence nearby	CCTV shows the crack or missing section	Patch repair, relining or replacing the section
Displaced or open joints	Paper and debris catch on the lip	CCTV shows a step between pipe sections	Patch lining over the joint, or re-laying the section
A dip or sag in the pipe	Water sits in the pipe and waste settles	CCTV shows standing water over a length of pipe	Re-laying the section to the correct fall
Poorly designed connections	Blockages after an extension or new bathroom	CCTV shows a sharp bend or a badly made junction	Correcting the connection
Pitch fibre pipes	Blockages in homes built mainly between the 1950s and 1970s	CCTV shows the pipe flattening or blistering	Relining or replacement

For a closer look at the everyday items that cause most blockages, see our list of things that should never go down your drain. If it is only the toilet that keeps blocking and the drain outside runs freely, the cause is more likely in the pan, the trap or the soil pipe inside the house.

How an experienced engineer stops it coming back

These are the steps we follow on a recurring drain blockage, and what you should expect from any drainage engineer.

1. Ask about the history. How often it blocks, which fittings back up first, and whether anything has changed, such as an extension, a new tree or new occupants.
2. Find every inspection chamber. Lifting each cover shows where the water stops and narrows the problem to one section.
3. Clear it with a jetter, not just rods. A high-pressure water jet scours the whole pipe wall, removing fat, scale and silt as well as the blockage itself. Special cutting heads can remove roots.
4. Survey it with a camera. Once the pipe is clean, a CCTV drain survey shows the inside of the pipe on screen and records it, so you can see the cause for yourself. The survey report shows what was found and where.
5. Recommend the right fix. This could be as simple as a change of habits, or a repair to a specific defect.
6. Explain how to keep it clear. A good engineer tells you what caused it and what to change, not just that it is fixed.

The repair options

• Root cutting removes roots from inside the pipe. On its own it is temporary, because roots grow back through the open joint.
• Patch lining seals a short section, such as a cracked pipe or an open joint, from the inside with a resin-soaked liner. No digging is needed.
• Full relining puts a new resin lining through a whole run of damaged pipe, creating a smooth, jointless pipe inside the old one. Our drain lining page explains the process.
• Excavation and replacement is needed where a pipe has collapsed, has a severe dip, or the fall is wrong. It is the most disruptive, so it is kept for problems lining cannot fix.
• Planned jetting suits some drains, such as a long kitchen run that collects fat, where regular cleaning stops the build-up before it blocks.

What you can do to prevent repeat blockages

A drain that has been properly cleaned and repaired stays clear much longer if what goes down it changes too.

• Bin every wipe. Water companies now ask households to bin all wipes, including those labelled flushable. Only toilet paper, pee and poo should go down the toilet.
• Keep fat out of the sink. Let cooking fat cool, scrape it into the bin, and wipe greasy pans with kitchen roll before washing them.
• Do not rely on hot water. Pouring hot water after fat only carries it further down the pipe, where it cools and sets.
• Use strainers. A sink strainer and a hair catcher in the shower stop most debris.
• Keep gullies clear. Leaves and silt on an outside gully grid soon end up in the drain.
• Plant away from drains. Some trees and shrubs send roots a long way in search of water.
• Avoid regular chemical cleaners. They seldom shift wipes or roots, and they make the job hazardous for whoever has to open the pipe.
• Know where your chambers are. Lifting the cover occasionally to check water is flowing freely gives early warning.

When the problem is not your drain

If the blockage is in a pipe shared with your neighbours, or in the section between your boundary and the public sewer, it is likely to be the water company’s responsibility rather than yours. Our guide to who is responsible for a blocked drain explains how to tell. If we find the problem is in a shared sewer, we will tell you, so you can report it to the water company.

Some buildings insurance policies cover repairs to accidentally damaged underground pipes, such as root damage or a crack, and a CCTV survey report is the evidence an insurer usually wants. Check your policy wording before the repair.

What it costs with Vantage

In normal working hours there is no call-out fee. After the first hour, time is charged in half-hour steps, and any parts or repairs are quoted before we start. Evening, weekend and overnight visits are charged at the out-of-hours rates. Every rate is published on our prices page, so you know what you will pay before we arrive. CCTV surveys and drain repairs are quoted before any work begins.

Frequently asked questions

How often should drains be jetted?

Most household drains never need routine jetting if nothing harmful goes down them. Drains with a known problem, such as a long kitchen run that collects fat or a section with root ingress awaiting repair, may benefit from planned jetting. Your engineer can advise based on what the camera shows.

Do chemical drain cleaners stop blockages coming back?

No. They may soften a small build-up of soap or hair, but they do not remove wipes, roots or a defect in the pipe. Used often, they can damage some pipes and seals, and they make the drain hazardous for anyone who later has to clear it.

Can tree roots really get into drains?

Yes. Roots look for water and find their way into pipes through open joints and cracks. Once inside they grow into a mass that catches paper and wipes. Cutting them out clears the drain, but sealing the joint with a liner is what stops them coming back.

Is drain relining a permanent fix?

Relining creates a new, jointless pipe inside the old one, designed for a long working life. It cannot fix a pipe that has collapsed or has a severe dip, which needs digging and replacing. A camera survey shows which option suits your drain.

How do I know if my drain has a structural problem?

Blockages that keep returning to the same spot, a drain smell, damp near the pipe route or sinking paving above it all suggest a defect. A CCTV survey is the only way to know for sure, because it shows the inside of the pipe.

Recurring blocked drains in St Albans and across Hertfordshire

If your drain keeps blocking, we can clear it properly, find the cause with a camera and fix it so it stays clear. We work across St Albans and the rest of Hertfordshire, Bedfordshire and Cambridgeshire. See our drain blockage service, our page for St Albans, or call 01462 506374.