Said Grantee shall save and keep harmless the said City from an and all liability by reason of damage or injury to any person or persons whatsoever on account of negligence of the Grantee in the installation and maintenance of its mains and pipe lines along said streets, alleys and public ways, provided, the Grantee shall have been notified in writing of any claim against the City on account thereof, and shall have been given ample opportunity to defend the same.