Washing the inside of a reusable water bottle can be tricky, perhaps causing some people to wonder just how clean it actually is. Well, CrazyCap is designed to continuously kill microbes by replacing a bottle's existing cap with one that shines ultraviolet light into the water. It can even be used to purify water that's collected on the go.

Developed by Miami-based startup Microlyscs, CrazyCap should reportedly fit on most third-party 9, 12 or 17-oz "cola-style" bottles.

When users want to check that regular tap water is free of nasties, they activate the cap's UVC-emitting LED by tapping a touch sensor on top of the device twice. In cases where they want to treat water collected from less trustworthy sources such as lakes or rivers, they tap it five times, causing the light to stay on for longer.

Exposure to the UVC rays should reportedly should kill up to 99.9999 percent of any bacteria, viruses, mold or algae present in the water.

One charge of the CrazyCap's battery should be good for treating 45 liters (9.9 US gal) of tap water, or 18 liters (4 US gal) of lake/river water Microlyscs

Additionally, the light will automatically come on throughout the day, once every two hours for a 20-second period – this is presumably just to get any microbes that may have been introduced when drinking. A sensor in the CrazyCap detects when it's screwed into a bottle, so the LED won't come on when it isn't.

According to Microlyscs, one charge of the device's battery should be good for treating 45 liters (9.9 US gal) of tap water, or 18 liters (4 US gal) of lake/river water. A colored light ring on top of the cap indicates the battery's charge level.

Should you be interested, the CrazyCap is currently the subject of a Kickstarter campaign. A pledge of US$38 will get you one, when and if they reach production. The planned retail price is $95.

Sources: Kickstarter, Microlyscs