|Hydrogen peroxide is simply a water molecule with an extra oxygen atom attached to it. Some folks have asked what effect it would have on a variety of equipment, so here it goes.
Hydrogen peroxide is an oxidizer. It oxidizes certain metals and organics as well. When you put a new shovel outside and it rusts, then it has oxidized from oxygen in the atmosphere. (If it were galvanized or zinc-coated, it would not rust).
So, if you pour hydrogen peroxide directly into the heater, it will oxidize only those things sensitive to oxygen. Anaerobic bacteria are organic and sterilized immediately. Carbon is an organic, so carbonate will be stripped from the heating element over time if hydrogen peroxide is added on a regular basis. A zinc-coated anode will help to "catalyze" or set off the oxygen, as will the walls of the heater if it is galvanized. Then, a thin layer of oxidized metal will protect the rest of the heater from corrosive bacteria. When water heaters rust out prematurely, I'm fairly sure that it's sometimes due to bacteria which secrete an extremely corrosive enzyme (H2SO4 sulfuric acid in some cases) which eats through even galvanized metal fittings.
Also, please take note, that if galvanized metal comes into contact with brass or copper, that it will create an electrical current which will dissolve the zinc over time. Galvanized fittings should not be used on copper pipe and brass fittings should not be used with galvanized pipe. The higher the dissolved minerals in the water, the higher the conductivity. There's an interesting and informative article about that here http://www.clihouston.com/knowledge-base/the-electrical-conductivity-of-a-water-supply-and-corrosion.html
If the If hydrogen peroxide is added early in the line, i.e. at the wellhead, then it will pass through whatever filtration you may have installed. Regarding greensand, it will do nothing more than oxidize and sterilize bacteria and any other organic substance in the sand and "clean it up", so to speak. It may have to be recharged with potassium permanganate more frequently if you add the peroxide frequently. Hydrogen peroxide oxides manganese upon contact, so it will actually do the greensand's job temporarily or permanently with constant injection.
Regarding water softeners, I had an in-depth conversation today with a softener specialist with whom I share a client (I do the peroxide thing). After treatment with hydrogen peroxide, this is what he found: 1) Because iron bacteria are not clogging the injection ports as before, the softener is working perfectly. 2) Because the calcium is oxidized from a carbonate to pure calcium, the softener works much more effeciently and uses much less salt for zero grains of hardness. 3) The hard water line outside does not build up calcium as it did before because its electrical charge has been changed and it does not precipitate as readily and stays in solution. This is very important in the livestock industry, particularly swine farms who rely upon water nipples which clog from calcium carbonate.
Iron filter...similar to oxidizing manganese, the peroxide will oxidize iron immediately and bring it out of solution, basically turning it to rust. The iron filter can take a breather, because the peroxide did its job as far as precipitation. The rust will still be filtered out, but no effect on the filter itself.
Ah, the carbon filter. Yes, carbon is organic and will be oxidized so the activated carbon filter may have to be changed more frequently. A good carbon filter will actually dissimilate the peroxide, or break it ALL down to oxygen and water as will UV light. However, as far as debris in the filter, if you have iron bacteria or other bacteria constantly plugging up the filter, then you've probably been throwing away a filter cartridge which actually had a lot more life left. The peroxide will definitely eliminate any anaerobic bacteria buildup in the filter and it may actually last longer.
One more thing...what if I have galvanized or copper pipes? Well, the answer to that is "fantastic", because when the peroxide oxidizes the zinc or copper, it leaves a very thin film of oxidized metal (which will not support bacteria), and will actually protect the pipes from further corrosion due to bacteria.
In summary, hydrogen peroxide has no ill effects, only positive.
OK...off the pedestal. Hope this was helpful