To repair your Delta bathroom faucet, identify the issue; then, purchase and install replacement parts to fix the problem. Before you begin, determine your faucet type to find the right troubleshooting guide. Delta bathroom faucets vary in design, so parts may vary from model to model.
Single-handle faucets frequently experience ball assembly issues as they get older. To repair an under-handle leak, take out your old ball assembly, and replace it with a new component. Single-handle faucets sometimes also suffer from aerator leaks. If your faucet is leaking from its aerator, remove and replace the fixture's seats and springs.
If your center-set and widespread two-handle faucet is leaking from under its handle, disassemble the fixture, and replace its stem unit assembly. If the faucet's aerator is leaking, remove and replace the unit's seats and springs.
In all cases, if your fixture's aerator leaks, and the problem is not resolved when you replace the faucet's seats and springs, try replacing the unit's ball assembly or stem unit assembly, depending on the model. To prevent future leaks, ensure you keep up with your faucet's regular maintenance schedule. Depending on the model, this schedule might include replacing rubber gaskets regularly and tightening bolts on a yearly basis.