There is Water just to the extent of Purification
Issue No.630-If the body or clothes of a person are najis and he possesses only enough water to perform wuḍū or ghusl, he should make his body or clothes ṭāhir and offer his prayer after performing tayammum. However, if he does not possess anything on which tayammum is valid, he should use the water for ghusl or wuḍū and perform his prayer with a najis body or clothes.