Rain water collection systems

I am interested in learning about rain water collection systems in PR. 

Our house has a flat roof with drain down spouts, that would be easy to plumb into a tank. A tank of large size could provide free water for gray water use , garden, car wash, etc.

Just starting to look into this possibility. 
If you have experience or guidance, please post.

One item .... need keep eye on the drains, they get clogged causing roof issues and water contamination.

Consider multi level filtration of the collected water.

Sorry to see little response to this.. I am curious as to the legalities of it as well as if anyone may be doing. There are several areas (even statewide now) that it is not legal to do so.

A couple cases of Ranchers out west having legal issues, but that is big scale collection. Only one case I have seen of a homeowner having a issue and that was really silly and I believe thrown out of court.

Collection of rainwater in cisterns is common in Puerto Rico.  Should be an easy matter, especially for non-potable uses.

Regarding the legality of it, that strikes me as a political question, and therefore strictly forbidden on this site.

Let's not get too carried away by labeling everything a political topic here. 

Rain water collection is legal in PR.  They sell the rain harvesting system ( tank, pump, connections etc) at the local Home Depot.

Having a large storage tank of rain water on hand when we get the next big blow would be very valuable resource.

After Maria, our friends who were on the island were saved by the fact that they had a swimming pool full of water they were able to use for washing, flushing toilets, garden etc.

But if you don't have a pool, the rain water tank will keep you going until the city water is restored.  You just need to stockpile enough drinking water. 

I think of it as a survival tool during emergency situations.  The systems I have read about range from very simple and cheap to large and sophisticated systems.   
A tank of 200 gallons would keep our household going very well for a long time and will get topped off with every heavy downpour.

My questions are how to keep debris out, how to set up the proper filtration and how to keep it sanitary.  The water is non potable, but I want to keep it as clean as possible and prevent algae or other stuff growing in the tank - perhaps a big shot of bleach every week would do the trick?

Yes, some parts of the US west may have restrictions on rain collection.   But not in PR.

They have an expression in Montana where water rights are frequently litigated  ( lived there for many years). “In the west, whiskey's for drinkin, water's for fighting”.  😎

Sitka wrote:

Let's not get too carried away by labeling everything a political topic here. 

Rain water collection is legal in PR.  They sell the rain harvesting system ( tank, pump, connections etc) at the local Home Depot.

Having a large storage tank of rain water on hand when we get the next big blow would be very valuable resource.

After Maria, our friends who were on the island were saved by the fact that they had a swimming pool full of water they were able to use for washing, flushing toilets, garden etc.

But if you don't have a pool, the rain water tank will keep you going until the city water is restored.  You just need to stockpile enough drinking water. 

I think of it as a survival tool during emergency situations.  The systems I have read about range from very simple and cheap to large and sophisticated systems.   
A tank of 200 gallons would keep our household going very well for a long time and will get topped off with every heavy downpour.

My questions are how to keep debris out, how to set up the proper filtration and how to keep it sanitary.  The water is non potable, but I want to keep it as clean as possible and prevent algae or other stuff growing in the tank - perhaps a big shot of bleach every week would do the trick?


My family in Puerto Rico never had water cisterns so I've been learning little by little as I go along. Last year I bought my home that thankfully already had one.  When I had the service technician come to give it a look over he explained it should be serviced by being cleaned once a year. Apparently, there's this tablet dropped in the water that helps do the trick for non-potable water.

We use a roof collection system to keep a pool filled at a rental house we own.  Very simple and works well.  We have a water filter installed in the line running from the roof to the pool and were amazed at what was caught.  Flat roofs grow algae which get washed into the system with each rain.  Pool chemicals fix that in the pool, but I would be cautious mixing roof runoff with water that would possibly be used for anything other than flushing. 

Keep rain runoff in a separate cistern and make sure it is chlorinated before mixing it with any potable water.

I highly recommend the rainwater harvesting guide from Texas A&M university as a TLDR.

always use a first flush filter between roof and collection tank. if you can have a collection/settling tank separate from the holding/storage tank, you will be able to minimize use of chemicals (sodium hypochlorite) and prolong filter life by letting it rain and fill the tank, letting the roof heavies and lights (stuff that washes off the roof) get flushed away from the system in the first flush, then collecting mostly clean/clear water, then letting that settle in the collection tank and pulling from the middle water (not the bottom of the tank nor the surface water but rather the water 6 inches above bottom and below surface) to fill the holding/storage tank. that water is then filtered before use and UV sterilized to ensure adequately clean and safe. Sodium hypochlorite can be used in the storage tank if desired, but is not necessary when the above system is employed