Why you cannot tell safe water by looking at it

Appearance is not evidence

Water that looks clear, has no smell and tastes normal can still carry bacteria, viruses or dissolved chemicals. None of the organisms that cause diarrhoeal disease are visible, and several of the most serious chemical contaminants, including arsenic and lead, have no taste or colour at the concentrations that cause harm.

The reverse also happens. Water can look cloudy or taste of minerals and still be within drinking water standards.

What actually counts as evidence

A potability claim should rest on a laboratory test, performed by an accredited laboratory, on a sample taken from that specific source, on a stated date. Ask for three things:

• Who tested it. An accredited laboratory, a local health office or the water district.
• When. A test result describes the water on the day it was sampled. Contamination can appear after a pipe break, flooding or a loss of pressure.
• What was tested. A bacteriological test says nothing about arsenic. A chemical panel says nothing about recent faecal contamination.

In the Philippines, drinking water quality is governed by the Philippine National Standards for Drinking Water issued by the Department of Health.

How this platform treats the question

BALDE PH keeps three things apart on purpose:

• Verification means the listing and the business behind it were checked. It says nothing about the water.
• Availability means somebody recently reported whether water was flowing.
• Water quality is recorded only when supporting evidence has been submitted and reviewed, with the issuing authority and the test date attached.

A verified provider is not automatically a verified potable water source. When you see no quality evidence on a listing, that means none has been provided, not that the water is unsafe and not that it is safe.