Installation at a Glance

Before installation

• Check the tank delivered is the correct size, capacity and configuration, including connection orientations and filter requirements.
• Inspect the tank before unloading and report any damage or missing items.
• Confirm suitable site access, unloading equipment and a clear route to the installation area.
• Check ground conditions, excavation depth, water table, nearby foundations, slopes/banks and utilities.
• RAMS must be completed before work begins.
• A structural engineer’s design is required where the installation involves vehicular loading, proximity to foundations/earth banks, abnormal depths, heavy clay or high water tables.

Excavation & base

• Allow sufficient excavation space for manoeuvring and ground conditions.
• Provide a 50 mm bed of 10 mm washed pea gravel.
• Ensure the excavation provides the correct minimum/maximum cover for the specific tank.
• Account for potential groundwater ingress and stabilise the excavation where necessary.

Positioning the tank

• Tanks must only be lifted and manoeuvred when empty.
• Use the designated lifting points with appropriately sized lifting equipment.
• Ensure the tank is correctly aligned with the inlet, overflow and service duct.
• Allow for approximately 10 mm of settlement when positioning the tank.
• The service duct should align with the controls inside the building; on direct-pressure systems, it must slope towards the tank.

Pipework & connections

• Minimum pipe fall is 1:100 in the direction of water flow.
• Connect the rainwater inlet, overflow and service duct once the tank has settled.
• Keep all pipework clean and protected from site debris.
• Be aware of filter invert drops: 66 mm for PF filters and 300 mm for VF-1 filters.

Backfilling

• Initially fill the tank to one-third full to settle it into the pea gravel and finalise alignment.
• Backfill with 10 mm washed pea gravel, keeping the backfill and water level rising together.
• Continue pea-gravel backfill until the tank crown has 50 mm of pea gravel cover.
• Continue filling the tank with water as backfilling progresses.
• Complete the remaining backfill to finished ground level using free-flowing material.
• Do not mechanically tamp the infill or finished ground level.

After installation

• Install and secure the tank neck/lid and seal the neck joints against groundwater ingress.
• If applicable, install the filter and cover it with strong polythene until the system is ready for commissioning.
• Clearly mark the tank location.
• Establish a 4 m exclusion zone around the original excavation footprint to prevent construction vehicles driving over the tank.
• The standard installation is designed for pedestrian and light ride-on mower loading only; vehicle loading requires appropriate structural design.