Clogged drains are the #1 service call in our area. A normal residential AC can produce up to 20 gallons of water per day. AC drains and drain lines are the perfect breeding ground for algae, which builds up until a clog is formed. In some cases, years of improper service can lead to drains not being able to remove the water being made, and require replacing. There is limited service that can be applied to a drain- algaecide should be used every 6 months, and routine vacuuming is required. Drain issues happen to 100% of AC systems in our area- it’s a matter of “when”, not “if”.