That's usually air in the lines, which is normal after a filter change, but if it persists, there's an issue.
DIAGNOSIS: Air trapped in the system or a problem with the storage tank's air charge.
FIX: After changing filters, you'll always get some air. Run the faucet for a good 2-3 minutes to flush it out. If it continues:
- Check the tank air pressure. With the tank empty (water valve closed, faucet open until water stops), the pressure should be 7-8 psi. Low pressure causes weird delivery.
- Listen near the filter housings. A gurgle there could be a loose connection sucking air.
IF THAT DIDN'T WORK: The check valve in the membrane housing might be failing, allowing water to back-siphon and create air pockets. Also, a cracked housing on a pre-filter can suck air. Inspect all housings for cracks.
HEADS UP: If the spurting is accompanied by spitting tiny black particles, that's carbon fines from a new filter. Flush the system for 5 minutes. If it doesn't stop, the carbon block filter may be defective.