Before calling a drainage engineer, confirm who owns the drain.

Southwark Council confirms that a drain is the property owner’s responsibility until it connects to either someone else’s drain or to a public sewer.³ A private drain, for these purposes, is one that serves only your property.

Thames Water owns and maintains public sewers under roads and footpaths — and is also responsible for shared sewers serving more than one property, even if those sewers run under a garden or driveway.² If the blockage is in a public or shared sewer, report it to Thames Water on 0800 316 9800.

Property owners are responsible for drains within their boundary that serve only their property. Thames Water is responsible for shared sewers and most lateral drains — even where they run outside or beneath private land.⁶

How to tell where the blockage is

Thames Water advises that the blockage may be within your property if:¹

• Your neighbours are not having drainage problems
• Your property does not share a drain with others
• Upstairs facilities are affected but downstairs is working — suggesting an internal blockage
• The drain or sewer access point is clear

If your neighbours are also experiencing problems, the blockage may be in a shared or public sewer — report it to Thames Water.

What causes blocked drains

Thames Water confirms sewers are only designed for water from toilets, sinks, baths and showers along with human waste and toilet tissue — everything else should go in the bin.¹

The most common causes of blocked drains include:

• Fat, oil and grease solidifying in pipes
• Wet wipes — including those labelled “flushable”
• Sanitary products, cotton wool and nappies
• Food scraps and coffee grounds in kitchen drains
• Soap scum and hair build-up in bathroom waste pipes
• Tree root ingress in older external drainage runs

What a drainage engineer will do

A drainage engineer will typically diagnose and clear a blocked drain using one or more of the following methods:

• Drain rodding — mechanical rods pushed through the pipe to dislodge the blockage
• High-pressure water jetting — high-velocity water to blast through debris and clean pipe walls
• CCTV drain survey — a camera pushed through the pipework to identify the cause, location and condition of the drain
• Chemical treatment — used by professionals in specific cases for grease and organic build-up; not all systems are suitable and misuse can damage pipework

Building Regulations Approved Document H requires adequate access for maintenance and clearing blockages.⁴ If your property lacks accessible inspection chambers, a drainage engineer can advise on the most appropriate approach.

We always recommend a CCTV survey for any recurring or unexplained blocked drain Southwark job — rodding or jetting clears the symptom; a survey identifies the cause.

Blocked drains in Southwark flats and converted properties

In purpose-built flats and converted properties across Bermondsey, Borough and Elephant & Castle, drainage systems can be shared between multiple units via stacks or shared lateral drains.

If your neighbour is also experiencing drainage problems, the blockage may be in a shared stack or lateral drain. Confirm responsibility with your managing agent before booking a private engineer — shared drainage faults may be the building owner’s or managing agent’s responsibility.

If water is backing up into your sink, toilet or bath from what appears to be a sewer, call Thames Water on 0800 316 9800.²

Landlord obligations for blocked drains in Southwark

If you are a landlord, blocked drains in your Southwark property are your responsibility to resolve — internal drainage must be maintained in working order.

Southwark Council confirms that internal plumbing — including drainage — is the responsibility of the homeowner or landlord.³

If a drainage fault poses a risk, private tenants can report unresolved repairs directly to Southwark Council’s housing team. The council aims to respond the next working day to urgent cases.⁵

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What blocked drain clearance costs in Southwark — 2026

Indicative ranges only — no official pricing data exists for private drainage services. Always confirm pricing before work begins. Actual costs vary by blockage type, access, depth and method required. VAT may apply.

Service	Typical range (London 2026)
Standard drain clearance (rodding)	from £85
High-pressure jetting	from £100
Emergency callout (out of hours)	add from £80
CCTV drain survey (basic)	from £100
CCTV drain survey (full written report)	from £200
Drain repair (no-dig lining)	from £100/metre
Drain excavation (structural fault)	from £500

See the full London Plumbing Costs Guide 2026 →

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Engineers listed here are verified before going live — business identity, contact details and service coverage checked at time of listing.

No middleman fees — every lead goes directly to the engineer.

We limit listings per borough so every engineer gets fair, equal visibility.

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Sources & further reading

¹ Thames Water — Blockages and blocked drains https://www.thameswater.co.uk/help/water-and-waste-help/blockages
² Thames Water — Sewer pipe responsibility https://www.thameswater.co.uk/help/water-and-waste-help/sewer-flooding/sewer-pipe-responsibility
³ Southwark Council — Be prepared at home (pipes and drains) https://www.southwark.gov.uk/planning-environment-and-building-control/environment/flooding/be-prepared-home
⁴ GOV.UK — Drainage and waste disposal: Approved Document H https://www.gov.uk/government/publications/drainage-and-waste-disposal-approved-document-h
⁵ Southwark Council — Report a repair issue if you’re a private tenant https://www.southwark.gov.uk/housing/private-tenants-and-landlords/private-tenants/housing-support-private-renters/report-0
⁶ Thames Water — Private sewer ownership https://www.thameswater.co.uk/help/home-improvements/ownership-of-private-sewers-and-pumping-stations