The short answer is to stop sprinkler water from reaching the furniture in the first place, then make the furniture easier to dry when it does get wet. In a city setting, that usually means a mix of small adjustments, breathable covers, and a quick care routine rather than one big fix.
Start by watching your sprinkler system for a few days. Look at the spray pattern and see where the water actually lands. If the sprinkler is hitting your chairs, table, or cushions, adjust the nozzle so it waters the plants and lawn instead. Sometimes a quarter-turn or a lower spray angle is enough. If you live in a building or shared courtyard, ask the property manager or gardener to redirect the head rather than trying to change it yourself.
Raise furniture slightly off the ground if water tends to pool. Rubber feet, small plastic risers, or even a slatted wooden platform can keep legs out of standing water. This is especially important for metal furniture, because constant moisture around the feet is where rust often starts. Make sure water can drain away from the area, too. Clear blocked drains, sweep away leaf litter, and avoid placing furniture in the lowest spot on a balcony or patio.
Use breathable covers, not a tight plastic tarp. Plastic can trap condensation and create a humid little box around the furniture, which is bad for wood, wicker, and metal. A fitted outdoor cover that lets air move is better. Take cushions inside or store them in a dry box when you know the sprinklers will run. If furniture does get wet, uncover it and let it dry fully before covering it again.
Material care matters. Wipe metal frames dry after watering and touch up any chips before rust spreads. For wood, use a breathable outdoor sealant and reapply as needed, but don’t over-seal so heavily that moisture gets trapped. Wicker and rattan should be kept dry and checked for mold in damp corners. Fabric cushions should be brought in or dried quickly, because damp cushions are the fastest way to get mildew.
Finally, make a quick habit of checking furniture after the sprinklers run. A two-minute wipe-down and a little air circulation will save you a lot of repair work later. If you can, switch a small urban garden or balcony to drip irrigation or targeted watering, which keeps water where it belongs and away from your furniture.