Where do pipes leak?

Pipes leak and the size of a pipe doesn’t matter too much. Leakage is a function of water use rate, which is a function of fixture flow rate + leakage from the distribution system. A distribution system with lots of leaks provides more pressure to push water into homes, resulting in higher average flows for each home.

In most areas, peak demands are due to start-up transients on fixtures before they fully warm up — showers, clothes washers or dishwashers being run after being idle for a while, etc. Or possibly due to morning toilet flushes waking people up as their bathrooms fill back up during quiet times overnight.

So you can usually see peaks at night when most people sleep, and the water use rate is low. A study of homes in Philadelphia found minimal variability in usage during weekdays for non-occupancy times (when people are at work). Still, they saw peaks during evening hours on weekdays when activity picked up and increased usage on weekends due to increased occupancy (people come home from where they go).

Peak demand varies over a year with differing day/night cycle patterns — i.e., loads grow or shrink with changes in solar load; demand peaks around 9 am and 8 pm each day; during summer especially, many regions see afternoon thunderstorms which can increase use by putting sprinkler systems into action; etc.
(from the article “Understanding Residential Water Demand” by Art Hirschfeld, PE)

So what can be done to help reduce the impact of peak demand on water pipes? One solution is to stagger the use of appliances in homes. For example, if people are showering at different times, it will help to even out the flow rate and minimize the chance of a pipe leak. Other solutions include using low-flow fixtures and fixing leaks in the distribution system. No matter what steps are taken, peak demand will always present a challenge for water utilities. Thanks for reading!

Peak demand is an issue that water utilities face every day. By understanding what causes peak demand and how it affects water pipes, we can minimize its impact.
Peak demand is a problem because it puts excess stress on water pipes, leading to leaks. The pressure in the system at peak demand is called the pressure head. When a line fails due to excessive water pressure, a sudden pressure drop can occur as a result of losing flow through the failed section of the pipe — this change from high to low pressure can create destructive surges that put other parts of the system under too much strain and cause further problems. To reduce these harmful surges, maintain adequate storage capacity, and avoid potentially costly repairs to already failing infrastructure, utility managers must try to keep peak demand as low as possible.