Testing the water in the boat's water tank - checking water purity with the IntelliTEC WPT1000 Water Purity Tester - got a reading of 113 PPM - as good as some filtered / bottled water sources. Original reading when I bought the boat was ~50 PPM - but the water has been sitting for a long time - so will do a series of empty/refill cycles over the next few weekends.
Darrell Cleveland did an interesting dissection of the device for one of his university classes
Drinking Water Standards
In terms of Total Dissolved Solids (TDS), in the U.S., the Environmental Protection Agency (EPA) advises against consuming water containing more than 500mg/liter, otherwise known as 500 parts per million (ppm) of TDS, although many health specialists believe that ideal drinking water should be under 50 ppm or lower. The average tap water in America contains approximately 350 ppm of TDS although it is not uncommon for municipal or local water supplies to exceed this. If TDS levels exceed 1000mg/L, however, it is generally considered harmful to human health and should not be consumed.
Some EPA Resources on Drinking Water...
- Ground Water & Drinking Water Fact Sheets
- National Primary Drinking Water Regulations
- Title 40, Chapter 1, Subchapter D - Water Programs - Part 131 Water Quality Standards