One of the good environment parameter is the availability of clean and healthy water. Healthy water is the water which have less dangerous subtance under the maximum limit which the rules maked by the government. One of the dangerous substance in the water is nitrit which in certain level. Nitrit is the derivative compound of nitrogen that usually found in industrial disposal, houses and farming. The disposal which mingle in the water then make the existence of the nitrit higher. The water with higher level of nitrit can caused methemoglibenia, on the other hand nitrit is the good place for pantogenic bactheria especially like eschercia colli. This condition lead the consumen to diarrhea. The permitted standard and maximum limit of nitrit in the water for consumed is 1mg/L and in the clean water is 3mg/L, to know are the waters in a good quality, its need test utensils, with those reason writter make a test utensils for detection and knowing the quantity of nitrit 0,5-3ppm with LDR sensor and it will be controlled by ATMega16 Microcontroller. Based on the riset of nitrit test utensils, the conclusion is nitrit test utensils can be use with adding reagen named sulfanilamide acid and N-(1-naphthyl) ethylene diamine dihydrochloride (NED) we get error <5%. The writter desire is nitrit test utensils properly to use