Micro hydro power can charge your power bank while you shower

There are a couple micro-hydro power generators on Ebay. These are not full kits, you will need to hook up a USB charger board to it to limit the output to 5vdc, and you will have to add a female USB port. This one hooks to any standard US pipe water supply, like your shower, and is said to generate 5-12v of power. But tests show it only generates 5v with no load, and 4.2vdc with a load. 4.2vdc is not enough to charge your power bank, but if you add a power booster to boost it to 5vdc it should work. This means it will generate power while you shower, wash your hands, or while the toilet tank is filling with water. You get more use out of the flowing water.

This is the same style as above and is stated to generate 100ma, at no load, which sounds more accurate.

This one has no case and is an open turbine. Again, it is unlikely to meet it's stated specs with a load on it. The threads might be for standard US water supplies, but I can't be sure. Also note that a US garden hose thread is not the same as a US water supply pipe thread. But there are adapters to go from one to the other. Some specs for this item:

This one with a case, claims to output 8.8vdc to 15vdc. At $8.10usd out the door, higher than the first item mentioned above, let's hope it outputs 5vdc even with a load. 

1. Water inlet/outlet: 1/2"
2. Output Voltage: DC9.8~18.5V/no-load, 
3. DC8.8 ~ 15V/0.1K load Max power : 3.5W 
4. Output Current: 128 to 260 MA/0.1 K load
5. Water Pressure: 0.08 ~ 0.45MP
6. Maximum Water Pressure: 0.55MP

But these might be fun to try and play with them.