Construction & Siting Issues   When considering a Greywater system, various site issues need to be considered. The potential use of the system must also be taken into account. The system needs to be tailored to best satisfy its use. To determine if a Greywater system is appropriate, evaluation of the water table is needed. Greywater should never come in contact with potable water. Although Greywater is considered to be less contaminated then Blackwater, it still is not potable and often contains pathogens. Greywater should never be used in a vegetable garden where the produce could be consumed by humans. Greywater is best suited for grass, shrubs and trees. Greywater becomes contaminated quickly. While sitting for as little as two days, pathogens and bacteria begin to develop.       The size of the site should be considered when designing your system. When installing a Greywater system the amount of input into the system should be equal to the output. A simple equation can be used to find the amount of gallons per week produced by a family. Using the number of people who will be occupying the site and multiplying that number by 300 will determine the gallons per week. For example, a 4-person family will produce 1,200 gallons per week. To determine the amount of water needed for irrigation, multiply the square feet of space by 0.6 gallons per week. For example, 2000 square feet of land to be irrigated would require 1,200 gallons per week.       To install a Greywater system there must be a connection with a municipal sewage collection. Greywater systems cannot be used on a site with septic tanks. Also an overflow or release connection must be in place to allow the system to function properly.