Aqua-pro Filtration products offer a 90-day 100% satisfaction guarantee. If for any reason you are not satisfied with your purchase, simply call us or the dealer you purchased from. Our products are manufactured using the best grade raw materials that are procured from certified and market-leading vendors.These filter out large things from sewage water, like cotton wool and condoms that should not have been thrown down the toilet in the first place. Filters can also remove smaller particles like silt and suspended solids; dissolved ions and some filters catch bacteria and viruses. Filtration is the most widely used method in developing countries. One of these filtration methods is the sand filter. As the name implies, sand filters filter water through sand and gravel, thus mimicking nature as groundwater percolates through the ground. There are two types of sand filters: a rapid sand filter and a slow sand filter.