Data validation has the ability to save the environmental contractor millions of dollars by preventing payment for erroneous laboratory data, remediating contaminants supposedly "found" on site which exist only as lab contaminants, lawsuits due to defective data use, and a host of other potential problems. Data validation is required by regulatory agencies at some sites, but is highly recommended in nearly all cases. A very low-cost service, data validation insures such high-cost activities as sampling and laboratory analysis yield the proper results. It is a must in any environmental litigation.