DosingTanks

A dosing tank temporarily holds effluent or waste-water before releasing it in controlled batches, typically to a drainage field, mound system or sewage treatment plant. This “dosing” action, usually via a pump and float switch arrangement, ensures the receiving system isn't overwhelmed and disperses flow evenly across the full area rather than one spot. They're commonly fitted after a septic tank or treatment plant where the site conditions demand it.

Sizing depends on your dose volume requirement, pump cycle frequency and any buffer capacity needed in case of power cuts or high inflow. As a guide, the tank should hold at least one full dose plus reserve capacity, with your treatment plant or drainage field designer specifying the exact dose volume. If you're unsure, check your system's design specification or consult your installer before ordering.

Most dosing tanks in our range can be installed either above or below ground, but this varies by model so always check the individual product listing. Below-ground tanks need to be rated for the burial depth and groundwater conditions on site, and may require a concrete surround or anti-flotation measures. Above-ground installation is simpler but you'll need to consider frost protection and access for maintenance.

Our dosing tanks are typically manufactured from polyethylene (MDPE) or GRP (fibreglass), both of which resist corrosion from effluent and chemicals. Polyethylene tanks are lighter and cost-effective for smaller volumes, while GRP tends to be used for larger or below-ground installations needing extra structural strength. Neither material degrades in contact with waste-water, so either is a durable long-term choice.

Some dosing tanks are supplied as an empty vessel only, while others come pre-fitted with a pump, float switches and control panel — check the individual product description for what's included. If buying a bare tank, you'll need to source a suitable submersible pump and level controls separately, sized to match your dose volume and delivery head. We'd always recommend an alarm float as standard, to warn of high level in case of pump failure.

Dosing tanks forming part of a septic tank or sewage treatment system fall under Building Regulations Part H and, in England, the General Binding Rules for small sewage discharges. You may also need an Environment Agency permit if discharging to a watercourse rather than a drainage field. It's worth checking with your local authority or the Environment Agency before installation, particularly for new systems rather than like-for-like replacements.