Mopping issue

After mopping it is leaving residual dirt marks on floor. What can be the reason.

You may see lines, spots on the floor after mopping if -
1. Tap water/hard water is used in the tank. Use drinking water only
2. The mop pads are not washed for a long time in between the cleaning cycle. The dirty pad may drag along on the floor causing spots and lines. Wash the mop pads after 150 sq.ft
3. Local cleaning agent/detergent is used in the product. The chemical residue stays on the floor and causes visible lines/spots after mopping. Do not use local detergent/ cleaning solution
4. Mop pads are worn out. Replace the pads every 6 months