Absolutely! You always need to replace lost fluids with good, clean water. Chronic low-grade dehydration is a major health problem for nearly everyone, and the additional fluids lost during the cleanse mean even greater dehydration. Also, some people have a stronger response to Epsom Salts or salt flushes than others, and the dosage should be adjusted accordingly. A loss of 5lbs...mostly fluids...is rather excessive. You might want to use less Epsom Salts with subsequent flushes.