Mo. Rev. Stat. § 88.838
Joint district sewers may be constructed by the municipality wherever it may deem it necessary that a sewer shall be constructed in any part of the city, town or village containing two or more sewer districts. In such case it may, by ordinance, unite the sewer districts into a joint district sewer and cause a sewer to be constructed therein in like manner and in all respects as is provided in the case of district sewers; except in cases of joint district sewers, the city, town or village may, if deemed proper, provide in the ordinance creating the joint district sewer, that the municipality shall pay a certain proportion to be specified in the ordinance, of the cost of the joint district sewer. The cost of constructing the joint district sewer, except the amount, if any, specified in the ordinance, to be paid by the municipality, shall be assessed and paid in special tax bills against the property included in the joint sewer district, the same as is provided in the case of district sewers.
§ 88.838, RSMo