Most shower and tap water will be sourced from either wells or ground water. Hotels should be cleaning their wells regularly and you should have no problems brushing your teeth with this water. Every tourist board approved hotel should have a government tap onsite which is treated water and safe for drinking (this is what the locals drink) bear in mind at smaller hotels there is just one servicing the whole hotel.
Purchasing bottled water from the store you will pay a Rs5-10 cooling charge on top of the marked price.
Wifi is available at most hotels in Sri Lanka although some may not offer this free of charge. Dialog offer a pay per usage Rs50 card will give you approx 2hrs surf time.
Most hotels password protect their wifi and is for customer or guest use only. If wifi is given free of charge to restaurant customers please be generous to have more then just one drink whilst downloading and uploading.
I have been in a situation where customers have sat for half a day using the internet as well as the restaurant seating area, plugging in and charging their laptops and then only ordering one fruit juice, this just ruins the owners view on giving out free wifi and spoils it for the next customer.
if you feel like donating money you can visit this place ! also see www.dedunu.org
very nice children and they need it !