No trustee or employee of a sanitary district may be directly or indirectly interested in any contract, work, or business of the district, or the sale of any article, the expense, price, or cost of which is paid by the district, nor in the purchase of any real, personal, or other property belonging to the district, or which shall be sold for taxes or assessments, or by virtue of legal process at the suit of the district.
SDCL 34A-5-28