Just because a plant has decided to grow in a spot doesn't mean that's the right spot.......as you see with the trees so close to the house. If it is not enhancing the yard, move it or loose it.

Another concern is the trash from the flowers and pods. Do you want that close to the door? You know how trash builds up right in the corner by the doors....it's like a magnet, LOL.

Jacaranda need regular watering......about twice a month and less often when leafless during cold weather.

As for the water line, if the pipes are plastic the concern about root invasion is far, far less than with the old galvanized or clay pipes. Softer pipes such as for drip irrigation laterals can be squished by root pressure from aging and thickening roots.

I'm not sure that the root system of the jacaranda and the mesquite are compatible. The mesquite tend to be more shallow rooted where the jacaranda are more deep rooted which might make it difficult for the jacaranda to get adequate nutrients. Keep in mind that mesquites can get huge - about 45 feet across when they're mature. Although it's hard to imagine now when the trees are babies, it's very easy to overcrowd little trees and then none of them do well as they mature. Another thought on the mesquites: they wild ones are thorny as all get out. You'll be glad to not deal with them once they get bigger - like in a year - and you're having to prune them every couple of months. The Chilean mesquite is a great thornless variety and grows quickly from 15 gallon containers.

Crista

I can just respond from experience. I live in Phoenix. I have a jacranda on the south side of my house. It's probably too close, but they are pretty vertical growers so I am not disappointed. It's about 7-8 years in that spot and I recall it was maybe a 24-30 inch box when put in. Truthfully, I don't even have it on the drip system, and I water it sporatically now, maybe once a month? So I say it's hardy, low maintenance, little trimming, minimal feeding, and it's a nice looking tree. It's also about 20 feet from a mesquite, again, maybe too close. The mesquite is close to the lawn, so it actually gets too much water, and trimming is a hassle, and difficult as it gets bigger. I would say they would be fine on same water schedule.
good luck

Ditto the above. The previous owner planted a Jacaranda. I love it but its not a tree I would have chosen because of its high water use, plus the high amount of litter. Mesquite needs very little water once established, so yeah, if you do move it, don't put it with those seedlings. They don't mesh.