You bet! Just not so much as to make yourself sick... That would only dehydrate you faster.

didn't they got seperate water pipes for washing water and drinking water in the states ? the washing water aren't as clean like the drinking water. You don't wanna get bacteria and viruuses in you, before you had out on a long trip in the desert.

Actually, no. We do not have potable and non-potable taps. All the pipes come from the same main.

Its not a pleasant thought, but back in the 50's and 60's when everyone was worried about nuclear war, the government even suggested using the water in the toilet reservoir (not the bowl!) for drinking in a survival situation.

That depends on what you mean. There is only one set of municipal pipes plumbing the cities. It carries water from the one set of water treatment facilities. It breaks up and goes into each building. It's all the same water.
Some of it is plumbed out to toilets. Some of it is plumbed out to sinks. Some of it is plumbed out to garden faucets. Some of it is plumbed out to drinking fountains. Some of it is plumbed out to sprinklers. It's all the same water, it's just plumbed out to various different types of outlets for various uses.
I'm sure that the water fountains are cleaner than the sinks are cleaner than the toilets, but we're talking metal and ceramic there, not water. It's all the same water, and it all comes from the same source regardless of what types of outlets a given portion of it ends up coming out of.
Sure, I'd rather drink out of a water fountain than a sink faucet, but only because the metal and porcelin fixtures have more of a chance of being clean, not because the water itself is any cleaner.
Is it different elsewhere? PC2K, are your cities in the Netherlands plumbed with two different sets of pipes delivering two different qualities of water from two different municipal water supplies?
Or did I just misunderstand?
Stay safe,
J.T.

In our trips in the western USA, we have found many locations with nonpotable water in the restrooms and for other washing/watering purposes (e.g., flushing trailer septic systems). Signs have explicitly warned that the water is nonpotable. Is it actually somehow contaminated or just not certified as safe for consumption--who knows? The only safe course is not to drink it. Pollutants could be biological, mineral, or chemical. If it's chemical, purification is not likely to be practicable for a hiker. It's quite possible that some businesses may have decided it is more cost effective or otherwise practical to limit themselves to drinking from bottled water. Presumably businesses which prepare food on site will have potable water.

Incidentally, even if the water is considered potable, you still may not want to drink it if you have alternate water/liquid sources. For example, on a recent camping trip in Death Valley, my younger son & I drank water from drinking fountains. Neither my wife or older son, who did not drink the local water had any complaints. Obviously the water was potable. On the other hand, it was sufficiently mineral laden, that we had many urgent trips to the restrooms. In short the water was not really poisonous, but it certainly wasn't desireable either. We were happy to have brought our own water supply, especially since we neglected to bring a filter.

John

well some country's has sepperate line's for drinking and one for washing. The drinking line comes usually from the same source, but aren't filtered as well. In some places they use rain water for flushing and other non-drinking things. primarily in new constructed home's. Some newly build sewer systems also got sperate line...