Ivation Battery-Powered Handheld Portable Shower
The Ivation portable shower is a true go-anywhere shower, perfect for camping or hiking or what-have-you. Using the pump at the bottom of the 6.5-foot hose, it pulls water from virtually any sink, bucket, or basin to provide a 2.5 liter/minute (0.66 gallon/minute) shower flow.
The kit doesn't heat the water but it does filter it for you, which is great if you need to shower with something like lake water. If you really hate cold showers though, you could heat up some water in a kettle before adding it to your bucket, or if you can, leave the bucket to warm in the sun all day while you're away from the campsite.
This short video gives a good overview of what the shower looks like in action:
And this one shows you everything that comes in the kit, piece by piece:
Get the Ivation portable shower for $40 on Amazon.