Designing the bin store: slope, drainage and a dosing shelf

The room is 3.2 metres by 2.4, it holds six 240-litre bins, and the only gully is in the corner behind the door. That single detail means every wash-down pushes water across the doorway and into the corridor, and every spill has to be chased uphill with a squeegee. The room was built to a drawing that showed bins as rectangles and water as someone else’s problem.

Bin stores are cheap to get right at design stage and expensive to fix afterwards. If you are building or refitting one, these are the dimensions that matter.

Five dimensions worth writing into the brief

Floor fall of 1 in 80 towards a trapped gully, with the gully positioned so that it is reachable without moving a bin. A 100 mm kerb around the perimeter, so wash water stays in the room rather than finding the door. Door width of at least 1,400 mm, because a 240-litre bin on a slope is wider than a 240-litre bin on a drawing. Clear height of 2.4 metres, so lids can be opened fully with a sack on the shelf. And 900 mm of clear working space in front of the bins, which is the dimension most often cut and the one that determines whether anyone can tilt a bin for a check.

That last one matters more than it sounds. A tilt check needs about a metre of clear floor and a person standing beside the bin. Stores designed to the minimum footprint cannot accommodate the test that the whole compliance argument depends on.

The dosing shelf nobody thinks about

Put a shelf at 900 mm, 400 mm deep, with a 40 mm lip, on the wall opposite the bins. Not above them. A shelf above a bin invites overhead scooping, which produces a dust cloud of polymer and a fine layer of granules on the lid that turns into a slippery paste the moment it gets damp.

At 900 mm the operator stands upright, scoops at waist height, and can see into the bin. The lip catches the spill that inevitably happens, and a small lip is much easier to clean than a floor. Add a hook beside the shelf for the scoop, and a second hook for a dustpan.

If the store is unheated, remember that polymer and condensation do not mix well. A shelf against an external wall will be the coldest surface in the room and will collect moisture. Stand the container off the wall by 50 mm, or put the shelf on an internal partition.

Wash-down without a flood

Two design decisions determine whether wash-down is a ten-minute job or a two-hour one. The first is a dedicated wash point with a bib tap and a short hose, positioned so the hose reaches every bin without being dragged through the doorway. The second is a gully with a removable basket and a trap, sized for the solids that actually reach it rather than for clean water.

The common failure is a gully outside the room, on the apron, on the theory that water will find its way out. It does, along with everything else, and the apron becomes a slip hazard in winter. Keep the water inside, and let the gully do the work.

Retrofit when you cannot move walls

Most people reading this will be working with an existing room. Three cheap retrofits fix the majority of problems. A rubber threshold ramp at the door, which keeps wash water in and lets bins roll out. A plastic containment tray under the dosing area, which catches spills and can be lifted out and hosed. And a painted line on the floor marking the clear working zone, which stops the room from slowly filling with stacked cardboard.

If drainage cannot be changed, a wet vacuum becomes the wash-down tool. It is slower, but it removes the water rather than moving it around, and it stops the corridor problem entirely.

What good looks like on a Tuesday night

The test of a bin store is not how it looks on a site visit. It is whether the last person on shift can close it properly in the dark, in the rain, with a bin that is heavier than they expected. That means lighting at the bin face rather than the ceiling, a door that stays open on its own, and a bin layout that does not require reversing a heavy bin around a corner.

If you are planning a refit, walk the room at night with a torch before you sign the drawing, and try to move a full bin from the furthest position to the door. It takes ten minutes and it will change the layout. Practical measurements for the dosing point itself are covered in the solidification user guide.