This is a very broad question. You might need a lot of humidity for some Genera, for others with a strong wet dry cycle you might need not so much. I have two glasshouses with no misters but i grow Genera that will survive on lower humidity. Agree with Jane, there is nothing wrong with most tap water. In fact the tap water here is great. I do water with rainwater but that is only because i want to water my orchids at appropriate times, not when allowed by the continuing water restrictions. As for reducing the temperatures. Again, that depends on what you are trying to grow. Just looked at the max/min thermometer at head height in my warm glasshouse. Not reset for several months and it says Min 10C/Max 41.5C . I know a few growers with glasshouses set up with misters and the plants to my eye look too sappy. It all depends on what is in your collection. Ignore the above if you are trying to simulate tropical montane conditions. I'm using a complete fertilizer with trace elements to make for the lack of minerals in water from my rainwater tank.

Only happening with one bathroom sink, no hot water in toilet tank or bathtub cold faucet or kitchen sink? In large buildings hot water pressure is kept slightly higher than cold so that problems like this can be detected and fixed quickly because of costs involved in hot water loss. Ask your manager if the hot water system pressure was worked on or any new single lever sink faucets installed anywhere at the time your problem started. At a guess the water flow you hear is not an external leak but some sort of cross connect fault that is then slowly dumping through a leaking toilet tank or perhaps some system valve that isn't tightly shut. If this problem is stumping the person hired to fix it, your condo is not hiring very competent people.

Some valve bodies have an auto shut off feature which is designed to prevent scalding. If one side has no pressure, both sides are shut off inside the valve body. Or you dislodged some huge chunk of rust and it made its way to the shower valve. I can't see from here. Try dissembling the shower valve and flushing it out.

Maybe I need to back up a bit - I was thinking you'd had your eye on a particular system and just wanted to get away from the small CO2 tanks they use. The best water in my opinion is Reverse Osmosis water - so I use a large commercial unit in my utility room that's piped up to my kitchen separately - that can feed the fridge at some point, but for me it serves a countertop dispenser for now. You could also do an under-sink RO unit as your base. Then it would need to go into one of these system - like Grohe's or Seltazap listed above or something like that, up to a tap likely in your kitchen sink it sounds like. Some of these systems have internal filters (as does my countertop unit) - I just leave those alone but basically never have to change them. For your fridge, you don't have to rely on just the filter inside - depending on your kitchen layout, you could possibly tap it into the same RO system that feeds your tap, or if there's no way to get a water line between, I've also put much higher quality filtration systems into my fridge before by using a 3-cartridge unit mounted on the wall behind the fridge that then runs into the fridge itself - this will do way more than the small internal filter can do and can get rid of far more contaminants. Now where my comment about the SodaStream adapter comes in - most of these carbonation systems use some sort of CO2 canister obviously - they'll either have an external connection to any size tank you want, or they'll be designed specifically for the sodastream bottles (regardless of how they're labeled, they're all the same). Plenty of SodaStream users grew frustrated with these little cartridges and came up with adapters that'll go from the little bottle hookup to an adapter that'll hook to any size tank. It's not an option on mine because it's a countertop unit and leaving the door open to run a hose to the tank would look bad - but under a counter, it wouldn't make any difference.