I have also been dehydrated and had IV fluids in the hospital. One dr told me by the time I felt symptoms, drinking water would not help. I now take electolytes everyday. There are several choices at vitamin shop or online. I also ordered something called"salt stick caps" that are capsules with electrolytes--easy to take. NUnn tablets are also good. Drop in a bottle of water, very tasty. They also have electrolyte gummies which are easy to take when you are out.
Good luck.
Both times I was dehydrated, I did have to get IVs to get back on track. Then I started with the electolytes.