The parties to this case all participated in the installation of water and sewer lines servicing a residential development known as the Robins West Project. McGill & Sons, Inc., initiated the litigation by filing suit against the other parties, Flood & Associates, Inc., Houston Pipe Lines, Inc., and Ed Rozier Construction Company, charging them with creating delays which allegedly prevented McGill from completing its work by its contract deadline. Originally, McGill claimed that the delays were the result of a policy of deliberate harassment intended to injure it, but this theory is not asserted on appeal, and no evidence is cited in support of it.

None of the defendants had any contractual relationship with the appellant. Flood & Associates is a firm of consulting engineers which was employed by the City of Warner Robins, Georgia, to perform certain services with respect to the expansion and modification of the city’s water and sewer systems. Rozier Construction Company had a contract with the city to install the water and sewer mains which would service the Robins West Project. Houston Pipe Lines, Inc., subcontracted with Rozier to perform portions of the work called for under Rozier’s contract with the city. McGill & Sons contracted with the Robins West developer, who was never a party to this action, to install the pipes which would connect the individual lots in the development to the city trunk lines installed by Rozier and Houston.

Each of the defendants denied having caused any injury to McGill. Houston Pipe Lines also filed a counterclaim alleging that McGill negligently allowed mud and silt to flow into its sewer lines and thus into the trunk lines which Houston had installed on behalf of the city. Houston alleges that it was driven out of business by the resulting expense of cleaning out these lines.

The trial judge granted summary judgment to the defendants on McGill’s complaint and to McGill on *4Houston’s counterclaim. Both McGill and Houston filed appeals. Held:

in Case no. 55593

(Case no. 55593).

*41. The grant of summary judgment to the defendants on the claims raised in McGill’s complaint was authorized, as the record fails to show a breach of any legal duty owed to McGill. There is no liability for negligence since there was no injury to any person or property as a result of the alleged delays. "A person is not liable for the unintentional invasion of the interest of another in his contractual or employment relationships with third person^.” Morse v. Piedmont Hotel Co., 110 Ga. App. 509 (139 SE2d 133) (1964). There is no liability under contract since the defendants were neither parties nor privies to any contract with McGill. See generally Code § 105-106; Stuart v. Berry, 107 Ga. App. 531, 535 (130 SE2d 838) (1963); Mauldin v. Sheffer, 113 Ga. App. 874, 879-880 (150 SE2d 150) (1966).

2. It was error to grant summary judgment to McGill on the claims raised in Houston’s counterclaim. Houston’s allegations that McGill negligently allowed mud and silt to infiltrate the sewer lines which it (Houston) had installed state a valid cause of action for damage to property. See generally E. & M. Const. Co. v. Bob, 115 Ga. App. 127 (153 SE2d 641) (1967). Although there is evidence in the record which tends to negate these allegations, there is also some evidence supporting them. Accordingly, material issues of fact remain for disposition by a jury, making the grant of summary judgment inappropriate.

The judgment in Case no. 55593 is affirmed. The judgment in Case no. 55594 is reversed.