If there are nematodes in the cat's drinking water basin, the cat's water basin must be cleaned immediately and replaced with clean drinking water. At the same time, the cat must be dewormed to avoid internal parasite infection. It is best not to feed your cat tap water, because there are many bacteria in tap water, which can easily cause cats to develop internal parasites and affect their health. It is best to give your cat cold boiled water, mineral water, or other drinking water.