This is a pretty common thing in Florida for a few different reasons. It’s not always the water that smells. There is a good way to tell if it’s something with the water or the drains.

This is different than a well system where sulfur is the problem. If it is sulfur, all of the water in the home smells all of the time. This can not happen on city water as it is heavily treated with chemicals like chlorine and chloramine (chlorine & ammonia) that kills off the sulfur bacteria.

The most common issue is the drains. When you turn on the water and you get hit with a sewage smell which will go away in about 30 seconds, It’s typically on a bathroom sink such as one of the twin sinks in a master bathroom. This is because the drain line is an S-trap where the sewer gas is not vented through the roof. There is a vent cap under the sink. When you turn on the water the sewer gas sitting in that vent is allowed to escape back up through the drain, and this is when you smell the sewer gas and assume it’s the water. See the diagram to see the difference between an S-Trap and a P-Trap.

S-Trap vs. P-Trap
S-trap vent cap

This is also an S-Trap. When you turn on the water the sewer gas is sucked out through siphoning from the vent cap.

The best way to tell if it’s the water is very simple.

  1. If the smell goes away after about 30-45 seconds of turning on the water then its not the water.
  2. Turn on the cold water on the sink that smells, fill up a cup. Walk away from the sink and smell the water in the cup. If there is no smell then its not the water. Do the same with the hot water.
  3. Again, if it’s the water that smells it won’t go away, and all of the water in the home will smell.

If you do get a smell on the hot side when doing the test from #2 above, then the issue is the hot water heater and not the water system. This would require the water heater to be flushed and the anode rod be replaced with an aluminum anode rod. This can be caused from a bad anode rod or from city water contamination before the water filtration system was installed. It would be best while changing out the anode rod to do a chlorine flush of the water heater to make sure all bacteria is killed off.