Raindrip Automatic Watering Kit with Timer for Containers and Hanging Baskets
Our score: 7.8/10 out of 101-yr warranty · Batteries power · 20 sprinklers or emitters
Drip kits water the soil at each plant through small emitters, so far less water lands on paths and leaves. They run from a hose faucet at low pressure: most kits include a regulator that brings house pressure down to about 25 or 30 psi, and a filter that keeps the emitters from clogging. The real differences are what you are watering and whether a backflow device is in the box.

To make any drip kit water on its own, add a timer at the faucet: see the best hose timers.
Three watering devices plus backflow, filter and regulator; sold in Canada
200 ft of main tubing for up to 700 sq ft, with a three-year warranty
66 pressure-compensating emitters, backflow and regulator in one bed kit
4 kits, sorted by our score
1-yr warranty · Batteries power · 20 sprinklers or emitters
None (manual) power · 200 ft tubing included · Pressure regulator included
None (manual) power · 8 sprinklers or emitters · 25 ft tubing included
1-yr warranty · None (manual) power · 180 ft tubing included
On a house supply, almost always. Drip parts are made for low pressure, typically 20 to 30 psi, and a screen filter keeps grit out of the emitters. Most kits here include both; check the box contents before you buy.
Yes. It stops garden water being drawn back into the house supply. Three kits here include one; for the others, fit one at the faucet. Local rules decide which type is accepted, so check with your water utility.
Colorado State University Extension gives roughly 200 feet and 200 gallons an hour for a half-inch line; quarter-inch tubing should stay short. Each kit's guide gives its own limits.
Clogging usually means a missing or dirty filter. Fittings that pop off usually mean the pressure is too high or the fitting doesn't match the tubing. Clean the filter, flush the lines and keep the regulator in place.
Two lines of emitter tubing along the length is the usual layout, with closer spacing for small plants or sandy soil. DripWorks sizes its small bed kit for three 4 x 8 ft beds.
Take the parts at the faucet indoors (timer, regulator, filter and backflow device) and open the end of each line so the tubing drains. Rain Bird's landscape kit uses a removable end closure for this.
Image credits: Shixart1985, CC BY 2.0