I need to shut valve to fix bathrooms
Can you provide a picture from the right side?– JACKMay 16, 2020 at 22:55
This appears to be the plumbing for your water heater - as such, while there are shutoff valves for the cold into the heater and the hot out of the heater, the cold running to your various fixtures (and to here - the main water shutoff) is almost certainly somewhere else.
The water shutoff valves here are the red and blue metal handles that are shaped somewhat like:
Turn them 90 dgrees so the handles are out of line with the pipes they are on, not in line with them to shut off - reverse to turn on.
Check your water heater manual to see if you need to shut it down before turning the water off. That's pretty common.
The other red and blue handles near them appear to be for some sort of flushing procedure with the capped ports near them.
In summary, you can only turn off the HOT water supply to the bathrooms at that fixture. May 17, 2020 at 4:49
Very likely the Blue is the cold inlet to the water heater. May 17, 2020 at 21:10
Ecnerwal is correct the tankless water heaters tend to have mineral buildup on the heat exchanger and some water systems require at least annual flushing others more often. Make sure the chemical you use is safe for your unit some acid based cleaners will quickly wipe out an aluminum heat exchanger.– Ed BealMay 19, 2020 at 15:33
Typically the water SUPPLY shutoff valve is on the outside of the house, where your water comes in from the source (utility, well, tank etc.). Closing that valve is what you need to do if working on ANY of the plumbing in the house, otherwise water can flow back through other things.
Not in freezing climates, where it is far more commonly inside the house, in the basement - though in some places it's outside the house, in a deep hole and the utility needs to shut it off for you - which is inconvenient enough that most houses have an internal main shut off even if there is a curb valve. For pumped wells, you can also just shut off the power to the pump and release pressure, but there is normally a shutoff valve as well - and in freezing climates that is almost always inside the basement.– EcnerwalMay 17, 2020 at 19:16