We had the water tested:

Hardness 6

Dissolved Solids 153

"The safety of water based on parts per million (ppm) of total dissolved solids (TDS) is a matter of debate. The Environmental Protection Agency (EPA) recommends that drinking water have a maximum of 500 ppm TDS, and that any measurement higher than 1000 ppm is unsafe. However, the World Health Organization (WHO) recommends that water with TDS below 300 PPM is considered safe for drinking. Some say that a TDS level of 150 to 300 ppm is good for drinking, while others say that the most appropriate range is between 50 and 150 ppm."