Irvine Ranch Water District has been a pioneer in establishing site-specific water budgets for its customers. However, establishing a water budget requires certain data, and if landscaping is at the site, this means obtaining the square footage of the irrigated area. On-site measurements are time-consuming and not always cost-effective. Aerial photography can be more cost-effective per site, but still can be cost-prohibitive to obtain. This paper discusses a cost-effective methodology for sizing landscape areas researched by IRWD that is accurate in determining water budgets for single-family residences. This methodology can be adopted by any water agency. Its key requirements are as follows: ensure customer confidence in the allocation by including landscape areas that fall within 1 standard deviation of mean, not median lot size; develop allocations that truly promote efficient irrigation practices by including landscape areas that fall within 1 standard deviation of mean, not 2 standard deviations from mean; and, develop a method that can be used universally in any community for a nominal cost that does not require individual measurements, only lot sizes required. Lot size information typically is available from property tax assessors or real estate data. Includes 2 references, tables.