TankFittings

Most tank fittings are sized by BSP (British Standard Pipe) thread diameter, typically ½", ¾", 1" or 2", which should match the boss or aperture moulded into your tank. If you're unsure, measure the internal diameter of the existing fitting or aperture rather than the outside of the pipe, and check your tank's datasheet where available. Get in touch with our team if you need help matching a fitting to a specific tank model.

Where a fitting is intended for potable water use, we stock WRAS-approved options clearly marked as such in the product listing. For non-potable applications like rainwater harvesting or irrigation, WRAS approval isn't a requirement, though we still supply robust, weather-resistant components. Always check the individual product description to confirm suitability before fitting to a drinking water supply.

Basic fittings such as ball valves, outlets and straight connectors are generally straightforward for a competent DIYer to install, and come with clear instructions. However, if you're connecting to mains water, working with a sewage treatment plant, or the job involves below-ground pipework, we'd recommend using a qualified plumber or groundworker to ensure it's compliant with Building Regulations and Water Regulations.

Compression fittings use a nut and olive to grip the pipe and create a watertight seal, and can be dismantled and reused if needed — useful for maintenance access points. Solvent-weld fittings are permanently bonded using an adhesive, giving a strong, leak-free joint but no scope for future adjustment. Which you choose often depends on pipe material (MDPE typically uses compression, while uPVC commonly uses solvent-weld) and whether you anticipate needing to service the connection later.

The fitting itself is usually the same standard BSP thread, but how it seats can vary — GRP (fibreglass) tanks often have moulded bosses or flanges, while polyethylene tanks may use bulkhead fittings passed through a drilled hole with a rubber seal each side. It's important to use fittings and washers rated for the tank wall thickness and material to avoid stress cracking or leaks. If you're fitting a bulkhead connector to a polyethylene tank, check compatible wall thickness ranges before ordering.

A typical setup requires an inlet fitting with a debris filter or calmed inlet to reduce sediment disturbance, an overflow fitting positioned above the outlet to prevent backflow, and a draw-off or outlet valve, often paired with a floating suction filter to draw the cleanest water from just below the surface. You'll also want a suitable air vent to allow the tank to breathe as water levels change. We can advise on a complete fitting kit based on your tank size and intended use, whether that's garden irrigation or a full household system with a pump.