Cold Forge customers have been telling us that changing their water every 3 weeks is working for them. We have a customer who adds a little chlorine bleach (1/3 cup) to the water to ensure disinfection and that extends the life of his water, but I don't want chlorine in my water.

Because my 3rd floor apartment is so tiny, I have an unfiltered Cold Forge 4. When I started plunging daily, I was changing every weekend because I didn't like the way my water looks after 4-5 plunges, so I built a portable filtration/ozonation unit that allows me to vacuum out and treat my water instead of change it. That's partly because the tap water in Phoenix during the summer is about 92F and it takes three days (or 200lbs of ice) to get my Forge back down to freezing after a change.

Your tap water might be colder!