BS8558-Certified Water Tank Cleaning & Disinfection

Overview

WATER HYGIENE - TANK CLEANING & DISINFECTION

Water Storage Tank Cleaning London. Professional water tank cleaning, chlorination and disinfection services. BS8558 compliant with UKAS laboratory testing. Protect your building's water supply.

Water storage tank cleaning is the professional draining, cleaning, disinfection and recommissioning of cold water storage tanks following BS8558 procedures. Tanks are chlorinated at 50 mg/l minimum free chlorine for a 1-hour contact period, then flushed and refilled. Post-disinfection samples are analysed by UKAS-accredited laboratories. Annual cleaning is recommended under ACoP L8.

Applicable Regulations

• Water Supply (Water Fittings) Regulations 1999

Suitable For

• Hotels & hospitality
• Hospitals & healthcare

Specifications

• Chlorine Concentration: 50 mg/l minimum (BS8558)
• Contact Period: 1 hour minimum
• Frequency: At least annually
• Lab Accreditation: UKAS certified
• Tank Types: GRP, steel, concrete, plastic
• Standard: BS8558:2015

Our 6-Step Tank Cleaning Process

A thorough, documented procedure ensuring your water storage tanks are clean, disinfected, and certified safe.

1. Pre-Clean Inspection - Risk assessment and condition survey of the tank, identifying contamination levels and access requirements.
2. Isolation & Draining - Controlled isolation and complete draining of the tank, with safe disposal of sediment-laden water.
3. Removal of Sediment - Remove sediment, debris, and biofilm; internal surfaces scrubbed and defects repaired.
4. BS8558 Chlorination - Disinfection with sodium hypochlorite at 50 mg/l minimum free chlorine concentration for a 1-hour contact period.
5. Flushing & Refilling - Flush chlorinated water and refill with clean mains water to safe chlorine levels.
6. Post-Disinfection Testing - Post-disinfection water samples sent to a UKAS-accredited laboratory; full compliance certificates issued.

Warning Signs Your Tank Needs Cleaning

• Discoloured Water - Brown, yellow, or murky water at outlets indicates sediment or rust contamination.
• Unpleasant Taste or Odour - Unusual taste or smell suggests bacterial contamination or chemical changes.
• Visible Sediment/Biofilm - Sediment, debris, or biofilm visible inside the tank during inspection or at outlets.
• Failed Lab Results - Bacteriological test results exceeding safe limits for Legionella, coliforms, or total viable counts.
• 12+ Months Since Last Clean - Annual cleaning is the minimum recommended frequency.
• Building works near the tank - May introduce dust, debris, or contaminants.

Professional Water Tank Cleaning Services

Stored water in tanks and cisterns can become contaminated with sediment, rust, biofilm, and harmful bacteria including Legionella pneumophila. Regular cleaning and disinfection is essential to maintain safe, potable water and comply with ACoP L8 water hygiene regulations.

Our trained engineers follow BS8558 procedures for tank cleaning and chlorination. We drain, clean, inspect, and disinfect your water storage tanks before refilling and testing to confirm bacteriological safety. All work is fully documented with certificates and lab results.

Types of Water Tanks We Clean

We service all water storage tanks including cold water storage tanks (CWST), hot water calorifiers, header tanks, break tanks, fire suppression tanks, and rainwater harvesting tanks. Whether you have a small loft tank in a residential property or a large sectional GRP tank in a commercial building, we provide the same high standard of service.

Tank Inspection & Condition Assessment

Before cleaning, we conduct a thorough inspection of the tank and its installation. This includes checking the structural integrity of the tank body, verifying that the lid is secure, insect-proof, and light-tight, inspecting overflow and vent pipes for screening, checking ball valve operation, verifying insulation condition, and assessing pipework connections. Any defects identified are reported with recommendations for remedial action to bring the installation into compliance with current Water Regulations and WRAS guidelines.

Chlorination Standards & Procedures

We follow BS8558:2015 procedures for water tank disinfection. After cleaning, the tank is filled and dosed with sodium hypochlorite solution to achieve a minimum free chlorine concentration of 50 mg/l. This concentration is maintained for a contact period of at least one hour to ensure complete disinfection. The tank is then drained, flushed with clean mains water, and refilled. Post-disinfection water samples are collected and sent to a UKAS-accredited laboratory for bacteriological analysis.

Where heavy contamination is present, we may recommend super-chlorination at higher concentrations or extended contact periods. For tanks serving healthcare facilities, we follow the more stringent protocols specified in HTM 04-01 for the control of Legionella in healthcare premises.

Commercial & Residential Tank Cleaning

We provide tank cleaning services for all property types including office buildings, residential apartment blocks, hotels, hospitals, schools, care homes, industrial premises, and retail properties. From small domestic header tanks in loft spaces to large sectional GRP tanks holding thousands of litres in commercial plant rooms, our engineers are equipped and experienced to handle any tank cleaning requirement across London. Contact us to schedule your annual tank clean.

Knowledge Check

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Frequently Asked Questions

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