This is old info but since nobody else has commented yet it might be worth something. In 2008 there were lots of taps around the streets with beautiful crystal clear water running from them and (cold) showers by the beach that didn’t even have taps on them and just ran constantly. We drank it. Didn’t die.
If I remember correctly there was some guy called ‘Suki’ who seemed to own everything from a chandlery
to ice machines and petrol stations. He also had a dock
in Roseau where you could fill up from a hose, but it was untenable in any kind of swell as the surge would cause all sorts of problems while alongside. Great water all over the island though, and such a beautiful place! Spent two months there. Loved it.