ORP in raw water falling steadaly? What is the cause?
ORP means oxidizing power of the water or how much strength water has in cleaning itself. This clearly means you have a lot contaminants in the water and hence there is not enough oxygen or oxidants in water to clean itself. You will have to inject air or add oxidants to you water.
We do add Potassium Permanganate to the water before filtration and add chlorine for disinfection. But I am wondering why my raw water ORP numbers are changing. Would there be some kind of environmental change that the water would be coming out different? I was thinking maybe because it's winter that the numbers would drop? But I don't see any changes in previous years caused by seasons.
Have water analysis done, looks like you may have organics in the water. If the temperature drops then Oxygen and CO2 should easily dissolve in water. ORP measurements are almost never compensated for temp.