Water Saving From Unexpected Place

Water is precious.  Not only because it is a gift from Mother Nature, but also because it takes quite some resources and energy to treat the water and deliver it to you.  According to the US EPA, letting your faucet run for five minutes uses about as much energy as letting a 60-watt light bulb run for 14 hours.  No wonder the price of water goes up at a much faster pace than inflation!  Actually, among all the utility costs in the GTA, the price of water is rising faster than natural gas and electricity.  If you see a sudden increase on your water bills, it might mean you have a leak somewhere.

Here at Toronto Western Hospital, we run into a dilemma on water use.  We all know that the cooling towers require certain amount of make-up water since they rely on water evaporation to remove most of the heat from HVAC and process cooling.  The operators must make sure there is sufficient water in the tower sumps otherwise we’ll run a dry sump and the heat has nowhere to go.  However the float-type make-up water valves are difficult to adjust and do not work well.  To make it safe, people had to add more than enough make-up water to the system – sometimes they had to use 2×6 lumbers to “manually override” the float make-up water valves.  The byproduct was an overflow issue.  Every month, thousands of cubic meters of clean water were going down to the drain, on estimate.  To make it worse, it disqualified us for the City’s sewer surcharge rebate, a reward for buildings that send less water down their drains, lightening the load on city sewers.

After comparing a few available technologies, we chose a simple one with proven performance and low maintenance for make-up water control.  It uses stainless steel probes to detect the water level.  When water reaches the probe at a certain level set by operators, it would allow electrical current flow from the base probe and the one at a higher level.  The brain, a new smart controller, will receive the signal and decide whether to open or close new make-up water valves.  It can also send an alarm signal to the building automation system to warn operators whether the water level is too high or too low.  In the past, we would have to go to the physical building to get this vital information.

New probe type water level control.

Water meter readings of the first a few months show consistent water savings, around 1,600 m³ per month.  With more cooling towers in operation in summer months, it is estimated we’ll save over 2,000 m³ of water per month.  Total annual savings will be enough to fill half of an Olympic swimming pool!  Another good thing is TWH will be qualified for sewer surcharge rebates again for the lower level of make-up water used. This fantastic project saves money, keeps us cool and treads more lightly on Mother Nature’s greatest gift … water.

Project completed in mid-Nov. 2019.  The chart shows historical data and how much water used since then … massive savings expected!