In order for a steam cleaner to work, you need to make sure that its tank is filled with water. What a steam cleaner does is take that water and heat it past its boiling point to produce steam vapor. In order to release the steam, steam cleaners combine with high pressure and extreme heat. This is why steam is so great for disinfecting. The combination of high heat and high pressure kills bacteria and other allergens on all surfaces. This also makes steam cleaners environmentally friendly since no chemicals are necessary to use with pressurized steam.