Hi have been getting bad smelling water and sometimes cold water comes out black for a few seconds. So today I checked the softener it was ok so got to the presure tank as its 13 years old now and it was full of water so put air to it to get the water out after all the presure was gone and got some really nasty smelling stuff out of it after filling and draing it about 6 times water was getting clear. and tonight water was not smelling anymore.Anyways should I replace the tank as it might be a health risk as it gives the house water from the well thanks for any help in this matter.