Rainwater Harvesting in New Mexico

Is it legal in New Mexico to catch the rain that falls on my roof and put it in a barrel for later use? Kinda. Sorta. Maybe?

I love this question, which I’ve written about in the newspaper (sub/ad req) in the past, and which came up last week when I was talking to the local chapter of the AIA.

It’s crazy to think that it wouldn’t be. I mean, it’s water on my property, right? The dilemma is that if the water would have run off my property and ended up in a a river had I not stopped it, it would be someone else’s water under the doctrine of prior appropriation. They could sue me. Crazy-sounding, I know, but it’s the law.

So for benefit of those who are curious, below is the actual written policy, as promulgated by the New Mexico Office of State Engineer. How might I determine if the barrel out by the drain spout is “reduc[ing] the amount of runoff that would have occurred from the site in its natural, pre-development state”? I dunno. Sue me?
Ose Rainwater Policy


  1. Interesting. Offhand, I’d say a house and associated paving would considerably increase runoff and reduce groundwater recharge relative to the natural state of a typical lot, so if the law is concerned only with lost runoff you should be entitled to take a considerable amount.

  2. John – Two things jump out at me in that policy statement. It says that harvesting “should not” reduce the runoff that would have naturally occur. It does not say “shall not”. From a legal standpoint that difference could be very significant – “should” gives the landowner more leeway. It also says rainwater cannot be “appropriated” for other uses. This means you can’t establish a legal right to the water that you harvest, but you can still use it for the purposes mentioned. The law introduced in Arizona last session would have created legal rights to harvested rainwater, which was one of the major problems with it. The NM policy is a classic of wishy-washy regulatory agency drivel. It doesn’t give you any rights, it doesn’t really take away any rights, it just kinda leaves where you started – confused.

  3. Chris – I’d agree that the memo is wishy-washy, but I think it’s because the law itself here is murky, no one has litigated the question to clarify it, and no one in the legislature has stepped forward to make things clearer one way or the other.

  4. It reminds me of an old Nick Blomley paper who wrote about “property” and how it can be considered on a continuum. So the highest form of property would be the property right (to rain, in this case), vs other forms like “permits” or a license to do this. But this memo doesn’t even go that far. Can we call it a property “wink”? As in, we at the OSE pretend to dissuade you from lowering runoff, while you pretend not to do so? Just a thought….

  5. Eric – I like your framework. I think the “wink” is necessary, because on its face the law is ludicrous.

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