Underground water
tank cleaning
Welwyn Garden City
Internal cleaning of a 36,000-litre tank beneath a basement car park, intended for a development's grey water supply.
Cleaning beneath the car park
Britteco carried out underground water tank cleaning for Stagg Property Services Ltd at a new-build development on Broadwater Road in Welwyn Garden City, Hertfordshire.
The 36,000-litre tank was below ground within the basement car park. With the development approaching completion, the client needed the tank cleaned for its intended role supplying grey water to toilets.
The original enquiry covered draining and cleaning. Before the cleaning visit was arranged, the client confirmed that the tank had already been drained. The work therefore focused on the internal clean, rather than removing a full tank of water.
- Client
- Stagg Property Services Ltd
- Location
- Broadwater Road, Welwyn Garden City
- Scope
- Underground water tank cleaning
Restricted access.
A clearly defined scope.
Vehicle access, the tank's below-ground position and the site's entry requirements shaped the preparation for the cleaning visit.
Vehicle access
A full-size tanker could not enter the site. The client confirmed that a Transit-sized vehicle could fit within the car park, and Britteco planned attendance with a flatbed van.
Tank already drained
The client reported only a small amount of water remaining at the bottom. The confirmed requirement was cleaning the tank interior, not bulk emptying of its 36,000-litre capacity.
Site entry requirements
The site required pre-attendance online induction and an on-site induction. A confined-space entry permit was also identified as a requirement during the pre-works document review.
Planning for below-ground access
Preparation included site-specific Risk Assessment and Method Statements (RAMS), access arrangements and coordination with the client's site team.
The RAMS were shared and revised before attendance. The job record also includes a confined-space entry form, while the site team provided induction instructions for the operatives.
The client confirmed that 110V power was available and that site access opened at 8am. The cleaning visit was agreed for Monday 3 August 2026.
- 36,000-litre tank capacity confirmed by the client
- RAMS updated before the cleaning visit
- Confined-space entry and site induction requirements identified
Confined-space access and internal cleaning
The team accessed the underground tank through the existing openings and carried out the internal cleaning work.
Site photographs show the tripod and winch positioned over an access hatch, a ladder within the shaft and an operative working inside the tank with a helmet and harness.
The cleaning photographs show deposits being collected from the base of the tank, with material gathered in a container inside the vessel. The work addressed the remaining internal residue after the earlier draining had already been completed.
- Access through the existing tank openings
- Internal cleaning and collection of deposits
- Photographs recording the work and interior condition
Inside the water tank
Internal photographs show the tank surfaces, fittings and cleaning activity beyond what can be seen from the car park access openings.
Cleaning completed.
Recorded on site.
The cleaning job was marked complete on 3 August 2026. The project brought together below-ground access planning, site-specific documentation and internal water tank cleaning at the Broadwater Road development.
Job sheet and photographs
Following the work, the team requested a job sheet with photographs showing the cleaned tank for the customer. The job record includes site photographs and the pre-works documentation correspondence.
Need an underground water tank cleaned?
Tell Britteco about your tank, its location and the available access. Include photographs and any site entry requirements so the team can discuss the cleaning scope with you.
View all case studies →