The pH of HCl is 5. It is diluted by 1000 times. Its pH will be

[H+] = 10-5After dilution by 1000 times,  [H+] = 10-8When the concentration of H+ ion coming from acid is less than equal to 10-7 M, then the H+ ion furnished from water is also taken into account.H+=10-8from acid+10-7from water ; H+=1.1×10-7; pH=6.956 ;