Hereafter the Department of Public Works shall not do any sewer or water pipe construction work or make any sewer or water pipe connections, replacements, reconnections or repairs which are for the special advantage of or required by private individuals, and chargeable to them, either inside or outside the City, unless either:
A. 
The estimated cost thereof, as determined by the Director of Public Works, has been paid in advance by such private party; or
B. 
A bond in such amount and with such sureties as may be approved by the Director of Public Works has been given to secure the payment of the work when completed.
The provisions of this part shall apply even though their effect shall be to deprive parties of water supply or sewage service. However, the provisions hereof shall not apply when, in the opinion of the Director of Public Works, their enforcement will unreasonably delay work or repairs, the prompt completion of which is necessary for the safety or convenience of the public generally.