I don't see the benefit. A pot of water and a wash rag uses even less energy. If that's what you are concerned the most when you are showering.

A pot of water and rag is not comfortable. This is a full shower nonstop that's like a mini wastewater treatment plant for the hot dirty water and mixes it back in with new hot water. I would use this in a desert situation or RV or if energy costs went way up.

I don't disagree, but I shared it because it's cool to me and I like to promote clever "open source" DIY ideas. I'm not putting one of these in, because I have too much in my project backlog and it's not terribly important to me besides the cool factor.

very cool idea. I just moved to cistern country and am going with rainwater collection treated for potability to solve this problem. I am going to Strongly consider this. the energy usage reduction here is great, but the cost of filters at the schedule proposed might be a net negative. hard to figure the math off the cuff. rainwater has a lot of passive filtration options, and you aren't dumping a lot of soap and stuff into it. I'm at a disadvantage energy wise, because the layout ofy property requires any collected rainwater to be pumped, but a pure gravity fed rainwater collection system is probably better cost wise. for me it's probably a toss up. might install one as a hybrid just to be safe for power outages, etc. very interesting, regardless. hard to believe ideas like this are "fresh" but here we are.

Actually, I recall accidentally catching a segment of the Bill Cosby show recommending to put an empty soda bottle in the toilet tank to save water. This was so idiotic that it stuck in my memory. If you want literal shit to build up in your pipes, instead of fully flushed - go ahead and do that. Water saving toilet tanks do not function as advertised. Taking a hot shower is also a treat, mental therapy, and one of the absolute greatest blessings of our technological civilization. Don't shortchange yourself.

Filter is mostly activated charcoal and play sand, and the creator said it's possible to recover the charcoal with high heat diy. The biggest factor is the heavy UV sterilization, which is overkill for most systems but would work in even turbid water. It's not much different from a normal multi stage filter but with the UV sterilizers and charcoal (aquarium filter medium?) to capture soap and oil emulsions. He said it's every year or two for filtes, which would be pretty cheap. https://showerloop.org/

I think you miss the point of this. If you're recirculating hot filtered water + more fresh hot water, you have a hot shower. Potentially would introduce some gross stuff into your shower line, but listeria is already an issue in a ton of residential water tanks thanks to EnergyStar pushing for lower tank temps. As a pro tip, you can fix this yourself by installing a loop and cranking up your water tank temp. The loop simply introduces cold water to the extra hot water at the supply line and pushes it into your main. This is how systems used to be setup years ago but they've fallen out of favor because of muh climate.