Let me add a bit more on the subject.........
Water heaters are a source of hydrogen sulfide. Sulfur reducing bacteria live in oxygen deficient environments such as water heaters. Sulfates can buildup on the heating rods inside the water tanks, so flushing the system is important. Heat forces the gas into the air, so thats what you get when you immediately turn on your hot water faucet; hydrogen sulfide gas or the smell of rotten eggs. At its worst, a black slim can form and clog lines, plumbing and tanks if left alone for a long time. The preferred method of sulfur treatment is ozone. Seeing that H2S has a chlorine demand, it takes a bit of chlorine/bleach to shock the bacteria. Using filters is okay for home use when continuous line flushing is going on (dishwashers, washing machines, bathing, etc), but on vessels where we might get on the water for a weekend or two a month, opening the hot water tap and clearing the line might be required. I use only an in-line screen filter for particulate trapping. If you travel the back roads of southern towns you'll often see "cascading aerators". These are small buildings with a screened upper portion, whereby the groundwater is pumped up and allowed to splash on a series of boards to release the H2S to the air. After that, gas chlorination is used to dissenfect the potable supply. I know, I used to inspect them! The bottom line here is stay on top of the condition knowing that a stagnant hot water heater can cause a problem. Which ever way you choose to flush, treat, release or reduce the H2S problem is up to you.
Good luck
Bob
"88 Mark II
Georgia