Everything in the sanitary sewer system goes to the Town's wastewater treatment plant. The size of the treatment plant, as well as all the pipes in the sewer system, are sized based on the number and type of customers connected to that system. The Town recently completed a $40 million dollar upgrade of their wastewater treatment plant to increase its capacity to 5.3 million gallons per day. However, even with this expansion, the plant can receive more wastewater than it can handle during heavy rains. People don't use their sinks and toilets more when it rains, so all that increased flow in the sewer system is coming from inflow and infiltration. If the sewer pipes or the treatment plant receive more flow than they can handle, then untreated sewage backs up into houses and overflows into streets and streams.