I agree with Peter. There's nothing in the statute that would extend the power of a road association to include maintenance of non-road assets.
Are we to assume that the 4 parcels which are not part of the homeowners associsation also make use of the water and sewer lines and the conduit? If not, it's hard to see why they ought to be paying for the maintenance of systems which they do not use.
If they do use them, was there no recorded or written agreement which either attached responsibilty for maintence expenses of these elements to the properties which use them, or at least requires payment for use of those elements, subject to disconnection upon nonpayment?