Order to achieve the best possible Water Quality
Although treatment processes can significantly reduce the amount of contamination present in raw water, the costs and potential risks from residual amounts contaminants may be too high. This remaining risk will become more of an issue as the number of regulated contaminants increases and the level of risk that public is willing to accept decreases Some water systems may require additional steps in the treatment train, such as aeration or granular activated carbon ration, at greatly increased cost, The efficacy of these treatment processes is usually measured by the percentage of contamination they are capable of removing from the raw water, not necessarily by the absolute contaminant level they attain. Thus, even with the addition se treatment steps, the risks ronic or acute disease from the con- minants remaining in the finished ter may still be greater than the con- mer is willing to accept Allowing deg ation of a water source becau sence of or the ability to construct ter treatment plant, therefore, will not ximize protection of public health The Portland (Ore) Water Bureau re- tly completed a study for the AWWA search Foundation on watershed man- tment. The purpose of the study was