Short answer: most urban outdoor furniture can handle a gentle hose-down, but not every piece should be blasted with water. Commercial-grade benches, tables, and planters are usually designed with weather-resistant materials and drainage, so routine cleaning with low-pressure water and mild soap is generally acceptable. The exceptions tend to be cushions, electrical components, natural wicker, unsealed wood, and pieces with loose joints or damaged coatings.
Powder-coated aluminum and steel are common for a reason: they shrug off rain and are easy to wipe or rinse. A hose is fine, but keep the pressure low and avoid spraying directly at chips, seams, or screw holes where water can sit. Stainless steel can also be hosed down, though it benefits from a quick rinse and dry to reduce water spots and surface grime. Plastic and HDPE furniture is probably the most hose-friendly—just use a soft brush and mild detergent for sticky spots.
Wood needs a little more care. Teak and other outdoor woods can handle water, but repeated soaking is not ideal. Use a gentle rinse, avoid concentrating water on end grain and joints, and let it dry thoroughly. Concrete and stone are tough, but high-pressure water can erode sealant or force dirt into cracks. Synthetic wicker is usually fine; natural wicker is not.
Before you grab the hose, remove cushions, covers, and any electronics. Check drainage holes and weep channels so water does not pool inside frames or planters. Use low pressure, a mild soap solution, and a soft brush. Skip harsh chemicals, bleach, and high-pressure washers unless the manufacturer specifically allows them. After rinsing, wipe or air-dry the furniture, and tighten anything that loosened. If a piece has hidden speakers, charging ports, or delicate finishes, follow the care label or ask the supplier. In short: hose down with care, and most urban outdoor furniture will clean up nicely without damage.