Whatsapp Instagram Youtube Facebook Tiktok
CALL NOW: 023 8251 5737
portsmouth drains24 logo

Why Shared Drainage Systems in Portsmouth Terraces Often Cause Repeated Blockages

shared drains portsmouth terraced homes

Table of Contents

Many homes in Portsmouth, especially older terraced properties in areas like Fratton, Southsea, Copnor, Baffins and North End, share drainage systems.
These shared lines were originally designed for multiple households to discharge wastewater into the same underground pipe. While they worked well decades ago, today they are one of the biggest causes of repeated drain blockages across the city.
This guide explains why shared drains cause so many issues, the warning signs to look out for and the best ways to prevent ongoing problems.

What Are Shared Drains?

A shared drain (also called a shared lateral or shared gully) is a drainage system where two or more properties feed into the same underground pipe before it connects to the main sewer.
In Portsmouth’s older terraced streets, it’s extremely common for several homes to share:

  • Wastewater pipes
  • Rainwater inlets
  • Access chambers
  • Shared gully traps

This setup means one home’s drainage behaviour can affect neighbours’ systems — a major cause of disputes and recurring issues.

Why Portsmouth Has So Many Shared Drains

1. Dense Terraced Housing Construction

Large parts of Portsmouth were rapidly built between the late 1800s and 1950s. Shared drainage was standard because it was cheaper and simpler.

2. Limited Underground Space

Portsmouth is one of the most densely populated cities in the UK, with very little spare land. Early builders often combined drainage to fit infrastructure into narrow roads and alleyways.

3. Historic Combined Sewer Systems

Many areas originally used combined drains for rainwater and wastewater — increasing the chance of overload or misuse.

4. Ageing Drainage Networks

Shared pipes that have served 3–6 houses for over 70+ years often develop structural problems or heavy wear.

Why Shared Drains Block Repeatedly

1. Misuse by One Household Affects Everyone

If one home flushes wipes, grease, sanitary items or food waste, the entire shared pipe can block.

2. Silt & Debris Build-Up from Multiple Sources

Rainwater gullies shared between properties collect leaves, mud and grit faster.

3. Narrow Underground Sections

Old clay and concrete pipes were built smaller than modern systems, making them prone to blockage.

4. Structural Damage Accumulates Faster

Cracks, displaced joints or root intrusion affect every connected household.

5. No One Takes Responsibility

Many homeowners do not realise their drains are shared, so essential maintenance gets ignored.

6. Washing Machines & Dishwashers Overload Old Lines

Modern appliances discharge large volumes of water which shared drains were never designed for.

Common Symptoms in Portsmouth Terraces

  • Water backing up into sinks or baths
  • Shared gully overflowing
  • Drains blocking repeatedly
  • Bad smells travelling between houses
  • Gurgling when neighbours use their plumbing
  • Toilet water rising or bubbling
  • Slow drainage during peak usage times

If several homes experience symptoms at the same time, a shared system is almost certainly involved.

Who Is Responsible for Shared Drains in Portsmouth?

After 2011 — Southern Water responsibility

Most shared drains that serve multiple homes outside the property boundary are owned and maintained by Southern Water.

Inside boundaries

If the shared pipe sits within private plots before joining the public lateral, homeowners may share responsibility.

A CCTV survey is usually needed to determine exact ownership.

How Professionals Diagnose Shared Drain Problems

1. CCTV Drain Survey

This identifies the exact source of the blockage and maps shared pipe routes.

2. Sonar Tracing

Used to determine which properties connect to the same run.

3. High-Pressure Jetting

Clears full-length shared lines without excavation.

4. Root Cutting

Common in older Southsea and North End gardens.

Long-Term Solutions to Stop Repeated Blockages

1. Relining the Shared Section

A full CIPP liner creates a new pipe inside the old one, reinforcing the structure.

2. Repairing Displaced Joints

Many shared clay pipes suffer from misaligned joints that catch debris.

3. Installing Backwater Valves

Prevents wastewater from one home backing up into another.

4. Educating All Households

Clear agreements about what can and cannot be flushed make a big difference.

5. Periodic Jetting & Maintenance

Shared drains need more frequent cleaning due to increased usage.

Preventing Shared Drain Problems

  • Never flush wipes or sanitary products
  • Avoid tipping fat, oil or food scraps down the sink
  • Keep outside gully grates clear
  • Report recurring issues to Southern Water
  • Arrange joint maintenance between neighbours
  • Book CCTV inspections every few years

Local Insight for Portsmouth Homeowners

Portsmouth has some of the oldest, densest terraced housing in Hampshire.
As a result, shared drains are incredibly common but rarely understood by homeowners. A single misuse or structural defect can affect an entire row of houses.
Identifying that a shared system is present — and treating it accordingly — is the first step in preventing repeated blockages.

FAQ — Shared Drains in Portsmouth

Q1: How do I know if my home has shared drains?

A CCTV survey will map the connections and confirm whether neighbouring homes use the same system.

Q2: Can my neighbour’s actions block my drains?

Yes. Shared drains mean waste from multiple homes flows through the same pipe.

Q3: Who is responsible for fixing shared drain issues?

If the shared line is outside property boundaries, Southern Water typically maintains it.

Q4: Do shared drains block more often than private drains?

Yes — more households mean more waste, greater wear and faster build-up.

Q5: How can I stop shared drain problems?

Avoid flushing wipes, use strainers, maintain gullies and book surveys when issues repeat.

Facebook
Twitter
LinkedIn

  • 24 hour drain unblocking 24 hour drainage portsmouth 24/7 callouts 24/7 Drain Services 24/7 Emergency Plumbing Affordable Drain Services bathroom drains blocked drain portsmouth Blocked Drains blocked drains Guildford Blocked Drains Portsmouth blocked drains waterlooville blocked sinks buchan trap Buchan trap replacement building over manholes Building Regulations burst water main Portsmouth cctv bournemouth CCTV Diagnostics CCTV drain camera CCTV Drain Inspection CCTV Drain Inspections CCTV drain inspections Guildford CCTV Drain Survey CCTV drain survey Guildford CCTV drain survey Portsmouth CCTV Drain Surveys cctv drain surveys guildford cctv drain surveys portsmouth cctv drainage survey kingston upon thames cctv drainage survey Portsmouth cctv inspections cctv survey cctv survey portsmouth Chemical Drain Cleaners Christmas 2024 christmas drain problems CIPP Lining CIPP lining Portsmouth CIPP patch repair cipp relining CIPP repairs Clogged Drains combined sewers commercial drain problems Commercial Drain Solutions Commercial Drainage commercial drainage in portsmouth commercial drainage Portsmouth commercial kitchen drainage Cosham Cosham drainage Customer Service damp prevention Denmead descaling Drain Blockages Drain Cleaning drain cleaning hampshire Drain Cleaning Portsmouth Drain Cleaning Services Drain Clearance drain clearance in portsmouth Drain Clearance Portsmouth Drain Descaling drain experts Drain Inspection drain inspection portsmouth Drain Inspections Drain Installation drain insurance Drain Issues Drain Issues Portsmouth Drain Jetting drain jetting portsmouth drain lining drain lining cost drain lining Portsmouth Drain Maintenance drain maintenance Guildford drain maintenance tips drain mapping drain misuse drain ownership drain pest control drain protection Drain Rat Stoppers Drain Relining Drain Repair Drain Repair Portsmouth Drain Repair Services Drain Repair Specialists Drain Repairs drain repairs Guildford Drain Repairs Portsmouth drain repairs Waterlooville drain replacement Drain Rodding Drain Services drain solutions Drain Survey drain survey portsmouth drain surveys Fratton Drain Unblocking drain unblocking Guildford Drain Unblocking Portsmouth Drain Unblocking Southampton drainage company Guildford Drainage Experts Drainage Inspection drainage inspections drainage inspections portsmouth Drainage Installations Drainage Issues drainage liability Drainage Maintenance Drainage Materials drainage portsmouth Drainage Repair Farnham Drainage Repairs drainage responsibility Drainage Services drainage services hampshire drainage services portsmouth Drainage Solutions Drainage System Maintenance drainage system types Drainage System Upgrade Drainage Systems drainage works kingston upon thames drainage works Portsmouth Drains24 Drains24 Portsmouth Eco-Friendly Drain Solutions Eco-Friendly Solutions Emergency Drain Repair Emergency Drain Repairs emergency drain service emergency drain service fratton Emergency Drain Services Emergency Drain Solutions emergency drain unblocking Emergency Drain Unblocking Portsmouth emergency drainage emergency drainage Guildford emergency drainage Portsmouth emergency drainage service emergency plumbing portsmouth Emergency Plumbing Services Emergency Services Environmental Compliance Environmental Impact Environmental Protection Enzymatic Cleaners Enzyme Drain Cleaners Fareham Drain Maintenance Fareham Drainage Fareham Drains Farnham Plumbing fatbergs festive cooking drains Flood Prevention flooding prevention foul water pipes Foundation Protection Fratton French Drains garden drainage Gosport Drainage Gosport Drainage Solutions grease build-up grease in drains Grease Trap Cleaning grease trap problems Guildford drain services gully issues Havant Drainage Hayling Island Drainage Hayling Island Drains HDPE Pipes heavy rain drainage High Pressure Jetting high pressure jetting fratton high pressure water jetting High-Pressure Jetting High-Pressure Water Jetting hilsea drainage HMO drainage problems Holiday Drain Services home drainage maintenance Home Improvement home insurance drainage Home Maintenance homebuyer drain survey portsmouth homebuyer drainage survey Homeowner Guide Homeowner Responsibilities Homeowner Tips Hydro Jetting interceptor trap removal kitchen drain blockage kitchen drain problems kitchen drains Landscaping Lee-on-Solent Drainage Lee-on-Solent Drains Local Business Local Drain Specialists local drain specialists Guildford Local Drainage Experts Local Plumbing Local Plumbing Services local soakaway installation Local Water Companies manhole maintenance portsmouth manhole regulations UK manhole repairs Modern Drainage Solutions new drainage installation no call-out fee drainage No-Dig Drain Repair no-dig solutions Non-Dig Technology outdoor drains outside drains overflowing drains Pest Control pipe blockages pipe cleaning Pipe Damage pipe rehabilitation Pipe Relining Pipe Repair Options Pitch Fibre Drain Repairs Pitch Fibre Drainage pitch fibre drains pitch fibre pipe pitch fibre pipes Pitch Fibre Repairs Plumbing Plumbing Alternatives plumbing issues Plumbing Services Plumbing Solutions Plumbing Tips Portchester Drainage Portsmouth Portsmouth business drainage portsmouth drain repair Portsmouth Drainage Portsmouth drainage experts Portsmouth Drainage Services Portsmouth Drainage Solutions portsmouth drainage survey Portsmouth Drains Portsmouth Drains24 Portsmouth homes Portsmouth Plumbing Power Jetting pre-purchase survey portsmouth Preventative Care Preventative Tips Professional Drain Services Professional Plumbing Professional Service Property Maintenance Property Management Protect Property Value PVC Pipes Rat Control rat stopper for drains rat stoppers guildford replacement drains Residential Drain Repairs Residential Drainage Residential Services restaurant drain cleaning restaurant drainage Portsmouth Restaurant Plumbing Rodding Services rodent in drains Rodent Prevention rodent prevention drains root damage drainage root damage drains root intrusion fixes root intrusion portsmouth Root Removal scale removal Septic Tank Installation Septic Tanks shared drains shopping centre drainage Slow Draining Sinks slow drains Soakaway Inspection Soakaway Installation soakaway installation portsmouth Soakaway Problems Fratton Sodium Hydroxide Southampton Drainage Services southsea blocked toilet Southsea Drain Services Southsea Drainage sports centre drainage student housing plumbing student let maintenance Sulfuric Acid summer drain issues summer drainage issues surface water drainage surface water drains surface water flooding Sustainable Drainage Sustainable Plumbing terrace drainage tree root damage portsmouth Tree Root Intrusion Tree Root Intrusions tree root removal trenchless drain repair trenchless lining trenchless pipe repair Trenchless Technology UK Drainage unblocking services Unpleasant Odors uPVC Drainage uPVC Pipes victorian drainage warehouse drainage Portsmouth Wastewater Management Water Backups water company drains water damage water main damage laws Water Management Waterlooville Plumbers winter damp winter drain care winter drain maintenance winter drainage winter flooding