Water is the make-or-break variable for almost every Oahu yard. Too little in the wrong spot and your lawn patches out; too much in the wrong spot and you’re looking at standing water, fungal disease, eroding slopes, or seepage against the foundation. And because Hawaii has no winter shutdown, both your irrigation system and your drainage work year-round — which means small problems quietly compound instead of pausing.
This pillar pulls together the two halves of the water story: getting water to your plants efficiently (irrigation) and getting unwanted water safely away (drainage). Each linked guide goes deep on one piece, written for Oahu’s specific conditions.
Why water behaves differently here
- Hard water + salt air are hard on equipment. County water scales up nozzles and valves; salt air corrodes metal fittings on leeward and windward coastal lots. Component choice and maintenance cadence matter more than on the mainland.
- Microclimates are extreme. Windward Kāneʻohe can get several times the rainfall of leeward Kapolei. A system or drainage plan that’s right for one can be wrong for the other.
- Clay soils drain slowly. Much of Oahu sits on red volcanic clay that holds water — great for growth, tough for drainage on flat lots and a source of runoff and erosion on slopes.
- BWS rules apply. Anything tying into the potable supply has to keep the Board of Water Supply’s required backflow assembly compliant.
Start where your problem is
If your lawn has dry patches, your water bill is climbing, or a zone won’t run, start in the irrigation guides. If you’ve got standing water, soggy spots days after rain, or runoff and erosion, start in the drainage guides. When a job crosses into licensed or high-risk work — backflow assemblies, major regrading, foundation drainage — we’ll say so and point you to a vetted pro.