BA-X/ BB Biodisc 9 & 12 Person Spares

The Biodisc range is sized by population equivalent, and the internal components — rotor discs, spindles and drive assemblies — differ in dimension between the 9 and 12 person units. Check the data plate on your unit or the original invoice for the model designation before ordering, as fitting an incorrectly sized part can throw the rotor off balance. If you're unsure, measure the rotor shaft length and disc diameter and compare against our spec sheets.

The drive motor, gearbox and bearings see the most wear as they run continuously to rotate the biodisc, so these are the parts most frequently replaced. Rotor discs themselves can crack or become brittle with age and UV exposure if the cover is left off. Drive belts, spindles and coupling components also wear over time and are worth keeping as spares if your plant is out of warranty.

Straightforward like-for-like swaps of the motor unit are within reach of a competent DIYer or general plumber, provided the power is isolated correctly. However, anything involving the gearbox alignment, rotor balancing or electrical wiring is best left to a qualified sewage treatment engineer, as poor alignment causes premature failure and reduced treatment performance. Get in touch if you're unsure which category your job falls into.

Manufacturers typically recommend a service visit at least once a year, in line with the plant's discharge consent and Building Regulations obligations for off-mains drainage. During a service, the rotor discs, bearings and drive components should all be inspected for wear, scale build-up and correct rotation speed. Catching a worn bearing or slipping belt early avoids a full motor failure and an unplanned call-out.

Biodisc units have been updated over the years, so spares are generally specific to a production era as well as the 9 or 12 person size. We stock parts for both current and older BA-X/BB ranges, but it's worth confirming your unit's age and model reference before ordering to avoid a mismatch. If your plant predates the current range, send us the details and we'll confirm compatibility.

Common spares such as motors, discs and bearings are usually held in stock for prompt dispatch, since a failed drive unit means a septic system that's no longer treating effluent correctly. Less common or older parts may need to be sourced from the manufacturer, which can add to lead time, so check availability before assuming next-day delivery. If your plant has stopped working entirely, flag this when ordering so we can prioritise getting the right part to you quickly.