Hot water from a combi boiler system is totally fine to drink as it's direct from the same mains pipe your cold water is and is as fresh as your cold water is. It's supplied and heated on demand so it's exactly the same water you'd get if you turned the cold tap on or the hot tap on (other than what's been sitting in the pipe since you last turned the tap/s on). Obviously going to be a good amount cooler than hot water from a boiled kettle but safe all the same. If your hot is from a tank the that's a different matter. |