Capital fees are billed with the building permit. You can read about this in the Wastewater Treatment Connection Fee - §224X Waukee Municipal Code.
Below is section 224X.6. schedule of water connection fees.
Waste water connection fees shall be due at the time of submission of a building permit as described in Section 5 of this Ordinance. Issuance of building permits and/or Mobile Home Permits shall not occur until such time as any and all fees have been paid in full.
Fees shall be based upon the equitable costs of extending service from the Municipal Waste Water System to the property for which connection is sought. The fees will increase annually based on the following schedule to account for interest incurred by the City for the Waste Water System improvements. From the effective date of this ordinance, fees shall be imposed in the following amounts:
Residential Single Family - $600 Per Household Unit.
Residential-Non-Single Family - $1,265 Per Unit
Non-Residential - $95.70 Per Fixture Unit
The City Council reserves the right to grant variances from this schedule of fees.