Drinking the water-safe?
 

Travelling to BKK and Pattaya.
Is it safe to drink the water?

By "safe" you mean non-deadly? And you mean tap-water?

Probably, at least in Bangkok - where the water quality has greatly improved over the last 15 years - but most Thai people I know get bottled water delivered, as do I, and use that for drinking, ice, and cooking. Tap water is fine for laundry, general household cleaning, showering.

Obviously, in a life/death situation I'd drink the water in Bangkok, 50-50 in Pattaya, maybe 0:100 after a flash storm?

To clean your teeth it's OK but NO do not drink the water.

No way is the tap water good enough to drink.

There are some sites where you can monitor the water quality almost on a minute by minute basis.

Map

Tap water from the primary supply (streetside/at the meter) is probably safer than from inside any sort of establishment (home, office, hotel, etc.) because, for the most part, we pump water (up) into holding tanks, and then distribute it throughout the building. So the pump, holding tank, distribution pipes, even faucets can become contaminated quite easily.

Years ago the tap water here in Bangkok was pretty foul, both looking and smelling (sulphur). Now it seems pretty good, but again, highly dependent on location. The BMA is quite vast.

I don't drink tap water but have certainly swallowed some small amounts when brushing my teeth, no ill effects AFAIK.

Most Thais in my neighborhood get water delivered every week (and ice delivered daily), as do I (water). Some people cook with tap water, I don't.

I would advise you not to use the water machines in the soi's as well i have never seen one being maintained. We buy 30x6 packs 2lt bottles of Singha water then you get 10 packs free delivered cost 1600 baht.

I use tap water to brush my teeth and to shower. I would never drink it. Water in 7-11 is very cheap, so why play with the unknown? :)

In major hotel chains, you won't have any problems drinking tap water - from my experience. I'm talking Marriott, Hilton, Hyatt, etc.

Otherwise, as others have said, it's safe to brush your teeth or rinse your mouth with tap water but for drinking purposes you'd want to choose bottled water.

Chuckling at the thought of someone "showering" with a bottle of water in a Bangkok hotel, lol.

(Edit to add: Yes, I served in the military where this was sometimes necessary.)

Those might be 1.5L?

https://www.singhaonlineshop.com/2015/products/17

That's kind of the standard size here 750, 1.5, 6, 18.9.

And a lot of plastic.

Most delivery customers (home, business) opt for the 18.9 (5 gallon) bottles, which require a deposit but get re-used. That's what most Thais in my neighborhood do anyway. A few of us share a Sprinkle account, which bought out Nestle's home delivery system last year.

^Yes sorry 1.5 liter bottles all the empty's are sold to a recycling man who goes around our area every week, get about 60 baht back for all the empty plastic bottles.

At one serviced apartment we lived in they boiled water every day when they cleaned.

I wasn't comfortable with that because boiling takes out microorganisms but not particulates. So I lugged big 6 L bottles from 7-11 or whatever for drinking and tea.

In Hua Hin our homestay was equipped with water purifiers which, after some research, we decided to trust and use. No ill effects to report. ^

Even in a friend's high-end condo in BKK, the tap water smells foul. I would not drink it.

I think the Thai officials did a press conference a few years ago to declare the Bangkok water safe to drink, but I still wouldn't do it. They and other Thais probably have a lot more bacterial immunity. I probably get the runs nearly every time I go anyway, but much less fun is the more serious constant-pain bit where your immune system has to use all your energy to fight off whatever it is. That one can have you bedridden for a day or two and weakened for another day or two. I've had that maybe 7 times (including a shingles attack, but most were foodborne like the Bali belly). So that's the risk I usually weigh against the effort needed.

As for Pattaya, back in my first visit in 1992 the water was so yucky-brownish I took a picture to show people back home (alas, back in the film era...my greatest trips were in the last years of the film era).

Could be the supply, but just as likely the entire building's water supply system is unmaintained and contaminated? Mold/mildew here grows in seconds.

Many people install multi-stage filtration systems, usually under the sink in the kitchen for home use. These cost a few baht per day, can be installed quite easily, have user-replaceable filters which can be ordered online. Your friend can go to HomePro for a selection. Simple really.

I haven't noticed any tap-water odors in years, but again, highly-dependent on location.