The sanitary merits of touch-free or auto-flush lavatory fixtures are beyond doubt, and manufacturers should confine their claims of benefits to that single attribute.

Auto-flush systems was made mandatory for all public toilets in Singapore after the Sars crisis in 2002, purely on grounds of hygiene.

There are many myths regarding plumbing fixtures vis-a-vis water wastage (Do away with auto-flush systems: March 28).

Here are two common ones:

- Instant water heaters (tankless) are more water-efficient than storage tank heaters in housing applications.

Here is an example of marketing propaganda exaggerating the virtues of a product by claiming savings that do not exist.

Studies have shown that there is increased water wastage associated with instant water heaters. There is evidence that consumers actually use more water by taking longer showers.

In addition, there is a time lapse of about 30 to 60 seconds to activate the heating components in the heater. Thus, the initial discharge of water from the heater is cold, resulting in a longer waiting time for hot water.

- Watering of gardens on alternate days saves water.

Gardening experts will tell you that watering deeply once or twice a week is adequate and this is better than frequent shallow watering. Deep watering promotes deep root growth.

Chia Wai Chon