You spend most time of your day at office, which means maximum time of your water drinking time is spent in office. But have you ever taken a look at how safe your office drinking water is? Let's take a look.
Are you provided with a styrofoam cup/glass to drink water? Styrofoam cups/glasses are very harmful to you your health 
The nozzle of the lower part of the dispenser in which the water is poured may not be cleaned regularly.
Water bottles on the dispensers are made up of plastic which is not BPA free and is a one-time use bottle but it is reused several times.
Corrosive steel: Even if your dispenser or its tap is made of steel, it may be made with corrosive steel and the corroded material is mixed with water.
Hand germs: Have you ever seen your office boy placing the big water bottle on the lower half of the dispenser?Doe she have clean hands?
Water in the dispenser stays for a really long time in the dispenser made of plastic. Especially the next morning if a fresh bottle isn't placed on the dispenser, you'll be drinking water is kept in a plastic dispenser for 12 hours or more.