The father of a buddy of mine runs the water department in our town. He hooked me up with the water reports for all of the wells in our town. Given the fact that all of the wells feed into the main and there is no way to determine exactly which we'll supplies my house, I found the four closest wells and averaged them.
What were the standard deviations? If they are small then using the average profile as a base is OK. If they are large then you could have large variations as they switch from one supply to another. You really need to find out what the variation at your tap is. This can be done by measuring at least hardness and alkalinity and preferably those two plus chloride and sulfate. Alkalinity and the two hardnesses are easy to measure as is chloride but you need to buy test kits and they cost money. Also the chloride tests usually involve a mercury salt so you must be concerned with disposal. Sulfate is tough but there are crude kits out there.
If you find low variation then you can use the approach you are taking with the averages. If variation is large then you will have to measure for each brew and adjust your water treatment plan according to what you find. The other approach is to remove variability by removing the ions i.e. by installing an RO system. The water could still be variable but the variations are so small they can be ignored.
Here are the results. The water seems ridiculously hard and alkaline. Are there any other issues that stand out to the trained observer?
It is pretty alkaline - about three times as alkaline as is usually recommended. But it is not particularly hard based on the calcium hardness number you gave. If the magnesium hardness is more than the calcium hardness (rare) then you would have to consider the water hard but even then not ridiculously hard.
The alkalinity will need to be dealt with either by dilution or the addition of acid. As you must fight to get the alkalinity down it is pointless to raise it back up again by adding bicarbonate as you have proposed doing. Your sulfate is high. Raising it to 300 would give you water that exceeds the EPA's SMCL for sulfate by 50 ppm (SMCLs are not health related but rather aesthetically determined i.e. water with that much sulfate doesn't taste good). There are people that do like beer made with water with that much sulfate (and more)but I think you need to find out if you are one of those people. To do this brew a low sulfate beer, taste it and then add some gypsum in the glass. Improvement? Then use sulfate in the strike water. No improvement or degradation? Keep brewing with low sulfate water.
Don't get hung up on profiles. Learn what each ion does and what the general characteristics of the water
as treated by the brewer are for the style you are trying to brew and brew with water with those general characteristics striving for the best beer. The use of 'best' implies an optimality criterion and there are several of those only one of which (authenticity) requires that you mimic the water. I can brew a better Pilsner with water that does not resemble Pilsen's except broadly and I can brew a better IPA with a water that isn't very much like Burton's - better by my optimality criterion which is better tasting beer.
I can make specific recommendations depending on what you want to brew but it is much easier for me to refer you to the Primer. That's why I wrote it.
