The Drain Box: Keeping Water Out of the Air Path

It is a humid-air problem, not a leak

Water in the drain box is normal and expected. A compressor pulling forty or sixty litres of air a minute on a hot, humid day is also pulling in water vapour, and some of it condenses as the air cools on its way to the hose. The drain box collects it and holds it out of the breathing path. The failure mode is not water appearing in the box — it is the box filling up and not being emptied.

The daily routine

Open the box, tip the water out, and wipe the inside dry with a cloth before refitting the lid. Leave it open to air while the machine is stored — a closed box in a hot car grows a biofilm that smells of old socks, and once that smell is in the hose it takes many dives to clear.

When to look closer

If the box fills in a single dive, or the water comes out cloudy with the machine running normally, that points at the seal or at a hose routed in a way that traps condensate. Both are worth a call before your next dive day rather than after. The seal itself is a cheap part and sits in the six-month wear tier, so replacing it costs very little.

FAQ