What we know about Aliso Viejo
Aliso Viejo stands on the last 6,600 acres of the 22,000-acre Moulton Ranch, a piece the Mission Viejo Company bought in 1976. The County approved a master plan for it three years later, and March 1982 brought the first homes to market. Cityhood came much later: 93.3 percent of voters said yes, and on July 1, 2001 Aliso Viejo became the newest of Orange County's 34 cities. The Aliso Viejo Community Association, the first community-wide property owners' association of its kind in California, still maintains most of the slopes, medians and parks.
The Census counts about 20,500 homes here. The median one was built in 1995, half went up during the 1990s, and only 6 percent are older than 1980. Detached houses make up 36 percent, attached single-family homes about a quarter, and buildings of five or more units 34 percent. Owners live in 57 percent of the occupied homes, so more than four in ten are rented. If you rent, keep the owner's or manager's number at hand when you call: the written price has to be approved before any work begins.
Two districts supply Aliso Viejo. Moulton Niguel Water District covers most of the city and El Toro Water District a small part, and neither has a local source: the water is imported and treated either at Metropolitan's Diemer plant in the hills above Yorba Linda or at the Baker plant in Lake Forest. Diemer water averaged 236 mg/L of hardness in 2025 (13.8 grains per gallon) and Baker water 293 mg/L (17.1). At that hardness, minerals settle wherever water is heated or squeezed through a small opening, which in a 1990s home means the water heater, the faucet cartridges and the toilet fill valves.
A plumbing permit in Aliso Viejo is the business of the City's Building & Safety, found at City Hall, 12 Journey, Suite 100, with applications taken through the City's online self-service portal. Plumbing is inspected as its own permit type. A final inspection may also wait on sign-off from Moulton Niguel Water District, the Orange County Fire Authority or the County health department, so on a permitted job we keep track of each of those approvals until the City marks the permit final.
Close to Aliso Viejo are Laguna Woods, Laguna Hills, Laguna Niguel along with Laguna Beach. A call from any of them rings the same line as yours, with a person on it day and night, and the plumber for each sets out from Laguna Niguel. Whatever the address, the cause of the trouble is tracked down first, and the repair waits until you have seen its price on paper.
Aliso Viejo ZIP codes on our map
- 92656





