Why theoretically? Well, because it relies on a number of other factors too. For example, you need to make sure that there is no chlorine or chloramine in the water because this will kill the beneficial bacteria that live in your substrate (sand / gravel) and filter. (It might be unlikely that a bore well has chlorine in but it's worth checking anyway).
You'll want to check that the water doesn't have high levels of nitrate or trace amounts of ammonia.
In short, there's more to water quality than TDS but it's a good indicator. I've used water in tanks that has a TDS of 180 and I've used water that has a TDS of 7. As Allerleirauh suggests, buy a test kit and test the water you intend to put in before you add it to the tank.