The waste is collected in a huge basin, which can subsequently be flushed or deposited in a sewer or septic tank. In houses and other low-use situations, gravity-tank toilets give a low-pressure flush (20 to 30 flushes per day). In high-use restrooms (more than 30 flushes per day), where water pressure is too low for tankless toilets, pressure-assist toilets provide a powerful flush. In high-use (more than 30 flushes per day) commercial, public, and institutional restrooms, tankless toilets use a flush valve (flushometer) and a high-pressure water supply for strong flushing. In special use contexts, prison toilets and ligature-resistant toilets deter vandalism and tampering. When plumbing is absent or people are unable to use a permanent toilet, portable toilets and commode chairs are employed. Macerating toilets (also known as upflush toilets) are designed to be installed in rooms where the main waste line is out of reach.