In case of default in the payment of the principal of the bonds or interest due thereon for a period of six months, all of said property, to wit: The waterworks system, consisting of pipes, mains, machinery, buildings, standpipes, reservoirs, easements, rights-of-way, water supply and the real estate connected therewith, including any leasehold rights and all obligations due from private corporations, individuals or the city to the said waterworks system, or board of waterworks commissioners, on account of water furnished or consumed, and including the right, privilege and franchise to continue thereafter the maintenance and operation of said plant for a period of thirty years, shall be conveyed by said commissioners by a deed of conveyance to the bondholders to be held by them in the relative proportion that the bonds held by each shall bear to the entire issue; provided, that said property may be conveyed to a trustee designated by a majority of the bondholders to be held for the use of all the bondholders in the proportion aforesaid, and such conveyance shall vest a perfect title in said bondholders and their assigns or their trustee to said property, and said bondholders and their assigns or their trustee, shall thereafter have the use of the streets, avenues, alleys and other public places to maintain and operate their said plant for a period of thirty years, as aforesaid; and provided further, that the lien created by the said bonds and sections 91.090 to 91.300 may be foreclosed in a court of equity in a like manner as if a mortgage or deed of trust was given to secure the same. No general or personal judgment shall be rendered against the city except for such amounts as may be due from said city as rental for hydrants used by the city for the purpose of fire protection and washing and flushing streets, crossings, alleys and sewers of the city, and in case of foreclosure, the decree and sale shall convey to the purchaser, or person or persons receiving title under the decree, or by a sale under the decree, all the rights, title and estate which could be conveyed by a conveyance from the board of waterworks commissioners, as aforesaid.