[serf]

>for sailing boats with water makers when the UV module fails

UV add-ins for water makers are a peace-of-mind option for boats with very large tanks that have opportunity for fouling; they are by no means common in the water-maker loop except in the very high-end; the high pressure membrane filters do the job just fine.

plus side : most sailing offers all the UV you could ask for. Grab a bucket and hit the deck, no need for future-bottles.