Even with known variables in a very small network it couldn't be "fixed," since the whole network works on the principle that the neutral carries the imbalance current, so there's nothing to "fix." Loads in the different homes are changing all the time and the neutral current at the transformer will fluctuate accordingly, only ever dropping to nil if the loads on all three phases (or both poles of a 3-wire single-phase system) are identical, which in practice is going to be just about never.The three phase being unbalanced, and a difficult issue to keep balanced, is a point, but its not a point that can be fixed, to many unknown variables.
And as I said before, the current in any particular stretch of neutral between where two homes have their supplies tapped off will vary with the distribution of loads even if the transformer neutral current were nil. The neutral in your service cable will always carry the current from your house since you have a single-phase supply, just as the neutral in the service cable of your neighbor's house will do, and if you have other parallel paths between your homes (e.g. via your bonded and interconnected water lines) then some of the current will take that path.
I only mentioned the issue of balancing between phases to point out that maximum current at a particular point on a neutral cable does not necessarily correspond with maximum load in a given area.
Even if the resistance through the pipework is higher than that through the neutral cabling, some of the current will still take that path. The old saying about "Electricity will take the path of least resistance" is really rather misleading. Electricity will take any and all paths available to it in inverse proportion to the resistances of those paths. Even if one path has a resistance a thousand times higher than the other, a tiny proportion of the total current will still take that high-resistance path.The TN-C-S works on the principle that the neutral will be earthed at the substation, so that the neutral has the lowest resistance attracting the return current. If the water pipes in a house have a lower return resistance, then the current up to a certain amount will flow through the house earth to the water main.
I don't think anyone is disputing the value of currents you're reading - At least I'm certainly not, since with TN-C-S and all the bonding in place it's to be expected. And yes, obviously currents create fields which you can measure.We are not talking about guess work, i have an £150 fluke true rms clamp meter that im measuring the current flow with.
I'm not going to get into the debate about whether those fields may or may not have detrimental health effects, but if you really are determined to reduce the fields created by the current flowing between your neutral and pipework, then you would have to do something to increase the resistance of the path you don't want the current to take. You could start by adding an insulating coupling in the water supply line to break the solid metallic connection which I feel certain exists between your house and the water main and your neighbors. That should see a substantial decrease in the current (although personally I would prefer to keep as much bonded together as possible with TN-C-S). It won't completely eliminate the current, as there will still be paths via existing pipework and masonry to earth etc., but the resistance of that path will be significantly higher.
If you are determined to go further, then you will need to abandon TN-C-S so as to break the link between your incoming neutral and anything in your house which has a path to earth. There would still almost certainly be some current flowing on the bond between the supply neutral and sheath.