Property Plumbing Checklist for Homebuyers: What to Inspect

Plumbing faults are among the most expensive defects to remediate once you have moved in — and among the most frequently missed by buyers relying on a single viewing. Understanding what to look for, and knowing which questions to ask your surveyor, can reveal issues that affect both value and habitability well before you exchange contracts.

Key points

• Lead pipework remains in some properties built before 1970; the Drinking Water Inspectorate advises replacing lead supply pipes as a priority, and their presence can affect mortgage offers.
• RICS Level 2 and Level 3 surveys cover visible plumbing but do not include a pressurised test of water systems or a CCTV inspection of underground drains.
• Low water pressure at multiple outlets — below 1 bar for mains-fed systems — may indicate a supply-side problem requiring investigation by the water supplier or a plumber.
• The Water Supply (Water Fittings) Regulations 1999 govern installation standards for plumbing work in England and Wales; non-compliant work can affect insurance and mortgage lending.
• Shared drains between properties are common in older terraces; responsibility for maintenance and repair is governed by sewer records held by the regional water company.

What a standard RICS survey covers — and what it doesn't

A RICS Level 2 Home Survey or RICS Level 3 Building Survey will inspect visible plumbing — the surveyor will note the apparent condition of accessible pipework, the heating system, the cold water storage tank if reachable, and any obvious signs of leakage or damp. What it does not include:

• Pressure testing of supply pipes
• Inspection of underground drainage (unless accessed via an existing inspection chamber)
• Boiler service records or output testing
• CCTV survey of drains and lateral connections

For older properties — particularly Victorian terraces and pre-war semis — these omissions can be significant. Commissioning a specialist inspection alongside your RICS survey gives a fuller picture.

Which professional do I need?

Homebuyer plumbing checklist

Use this checklist during a viewing or pre-exchange inspection. Items marked ⚠ warrant further specialist investigation if concerns arise.

Water supply

• Turn on taps at multiple points (kitchen, bathroom, en-suite) — does pressure feel consistent?
  
• Check under-sink cupboards for signs of past leaks (staining, swollen MDF, mould)
  
• Ask the seller whether a water meter is installed and whether it has registered any unusual consumption
  
• ⚠ Ask about pipe material — grey or blue polybutylene plastic piping from the 1970s–90s can be prone to failure; dull grey soft metal pipes may indicate lead
  
• ⚠ Ask whether the cold water storage tank (if present) has been insulated and inspected recently
  

Hot water and heating

• Check the boiler make, model, and age (units over 15 years may need imminent replacement; indicative replacement cost £2,000–£4,500 installed)
  
• Ask for boiler service records — a gap of more than 12 months is a yellow flag
  
• Bleed a radiator (with seller's permission) — black water indicates sludge and may warrant a power flush
  
• Check for signs of condensate pipe or overflow discharge staining outside the property
  
• ⚠ Combination boilers in larger homes: check whether flow rate is adequate for simultaneous use across multiple bathrooms
  

Drainage and waste

• Check visible waste pipes under sinks and baths for staining, leaks, or inadequate fall
  
• Flush toilets; check for slow drainage or gurgling sounds (possible partial blockage or shared drain issue)
  
• Locate external inspection chamber — lift the cover if accessible and check for standing water or debris
  
• ⚠ Ask whether the property connects to the public sewer or a private system (septic tank or small sewage treatment plant)
  
• ⚠ In older terraces: ask whether the seller is aware of shared drains with adjacent properties
  

Lead pipework

• Ask when the property was built — properties built before 1970 may have original lead supply pipes
  
• Ask whether any lead pipes have been replaced
  
• Check the visible supply pipe in the kitchen — lead is dull grey, easily scratched with a key, and will not attract a magnet
  
• ⚠ If lead is suspected, commission a water test (some water companies offer this free) and ask a plumber to advise on replacement costs
  

Red flags — when to commission a specialist inspection

The following signs warrant a specialist drain survey or plumbing assessment before exchange:

• Gurgling or slow-draining outlets in multiple rooms
• Persistent damp or mould in a ground-floor bathroom or near an external wall close to drainage
• Evidence of previous insurance claims for escape of water (check the property information forms)
• An external inspection chamber with standing water or root ingress visible
• A property that has been vacant for more than six months (stagnant water increases legionella risk and pipe corrosion)
• Victorian or Edwardian terraced properties with no record of drain clearance or investigation

What to ask your surveyor about plumbing

Before instructing a RICS surveyor, ask:

• Will you inspect the cold water storage tank and advise on its condition?
• Will you comment on visible pipework material, including potential lead identification?
• Will you check the boiler age and visible condition?
• Do you recommend a CCTV drain survey for this property given its age and construction type?
• Will you note whether the drainage connects to the public sewer or a private system?

A good surveyor will flag concerns they cannot fully assess and recommend specialist follow-up. If they do not, ask explicitly.

When to get professional help

Plumbing defects invisible during a standard viewing — cracked underground drains, corroded pipework, tree root ingress — are among the most expensive post-purchase surprises in UK residential property. Commission a specialist drain survey if:

• The property is a Victorian or Edwardian terrace with shared or original clay drainage
• You can see standing water in an inspection chamber during a viewing
• Your RICS survey recommends further drainage investigation
• The property has been extended and drainage routes are unclear

A boiler service or condition report from a Gas Safe registered engineer is advisable before exchange on any property where the boiler is over 10 years old or carries no service records.

How Housey can help

Housey connects you with qualified surveyors for RICS Home Surveys, specific defect surveys, and CCTV drain surveys, so you can commission the right combination of inspections before exchange and proceed to completion with confidence.

Frequently asked questions

Will my RICS survey flag plumbing problems?

A RICS Level 2 or Level 3 survey will note visible plumbing defects and poor condition, but does not include a pressurised pipe test or a CCTV drain inspection. Your surveyor will usually flag concerns and recommend further investigation. If warning signs exist but your surveyor does not recommend follow-up, you can commission a specialist survey independently.

How do I know if a property has lead pipes?

Lead supply pipes are dull grey, soft enough to scratch with a key, and will not attract a magnet. They are most common in properties built before 1970. Your RICS surveyor may note visible lead pipework; a plumber can confirm during a pre-purchase visit. The Drinking Water Inspectorate advises replacing lead pipes to eliminate any risk to water quality.

What does a CCTV drain survey cost?

A CCTV drain survey for a standard UK residential property typically costs £100–£300 depending on the number of drain runs and the surveyor's location. It produces a video record and a written report noting defects, roots, fractures, or misaligned joints. This is usually far less than the cost of emergency drain repairs discovered after purchase.

Are shared drains my responsibility?

Private drains within your property boundary are generally your responsibility. Shared drains serving more than one property, and public sewers, are usually maintained by your regional water and sewerage company. The legal position depends on adoption agreements and property age; your solicitor should review the drainage information in the property information forms before exchange.

Sources and further reading

• Lead pipes and your water supply — Drinking Water Inspectorate
• Water Supply (Water Fittings) Regulations 1999 — legislation.gov.uk
• Home surveys: choosing the right type — RICS
• Drains and sewers: who is responsible — GOV.UK
• Legionella in domestic water systems — Health and Safety Executive