I think diluting your water 50-50 with ro or distilled would likely be ok. Again, without knowing the numbers it would be hard to say for sure but in all likelyhood it would be ok.
I like to brew with akron city water. It is a bit low in calcium but other than that it is a good all around brewing water. Here is a link to the numbers. http://www.grapeandgranary.com/ggrecpdf/clevewater.jpg
Cleveland and Akron water are almost identical.
g and g