Why shouldn't I drink the water in a reservoir or river?

Error message

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Notice: Trying to access array offset on value of type bool in refresh_node_load() (line 189 of sites/all/modules/refresh/refresh.module).

Why shouldn't I drink the water in a reservoir or river?

This water has many different living creatures that call the rivers and reservoirs home. They can make this water unsafe to drink until it has been treated and purified.