Gaining an Accurate Estimate of Water Demand in Buildings

Estimated peak water demand is customarily used to size a building’s piping system. But with Covid-19 and other pathogens, a higher demand for sensor-activated and high efficiency fixtures has increased the need for more accurate demand calculations given a large variety of water dispensing fixtures. 

A new approach to adapt the known method of convolution on discrete distributions is introduced for accurate water demand estimation. The new approach finds the cumulative distribution function (CDF) of water demand for an arbitrary number of different fixture groups with different probabilities of activation and different flow rates. The method is accurate for smaller buildings and individual restrooms with few fixtures, as well as for large buildings with high fixture counts. Using this approach, a design curve to look up the estimated peak for water demand will no longer be needed.