Whole house filtration ??? | Alternative Energy | Forums

What you are planning is similar to what I am planning, except water from the pond would be a last resort for supplying my home or as drinking water. A pond attracts life of all sorts. Plants, mammals, birds, insects, but also microbes including parasites, bacteria, etc. It will mature into an ecosystem, and ideally into a balanced ecosystem, but it can be unbalanced as well.

Rainwater has less opportunity to become contaminated. Most of the contamination occurs once it comes in contact with things. Your roof, the leaves and bird droppings on your roof, the bacteria lining your gutters, etc. A "first flush" is recommended to clear away such build up. The first part of the rain is used to wash away debris and dirt and is not captured. Once flowing clear, the water is then diverted to cisterns, sometimes flowing first through filtration to help further clean what gets into the cisterns. The water from the cisterns is then filtered again as it enters the home now clean, safe, and potable.

My plan will be to harvest rainwater, to use a first flush, to filter before storing in cisterns, and to filter again before using it. It is possible to collect enough rainwater that it should not run out. I simply padded every calculation. Even if it is just me, I planned on a household of 10 with high water use. I found out the average yearly rainfall for my area and predicted drought, then I went with 25% of the drought. It is recommended to store enough for 3 months at a time, so I planned to store enough for 6 months at a time. Once knowing how much I would need and how much would fall given worst case scenario, I used a formula that tells how much surface area is needed for collection.

Rainwater harvesting comes down to those 2 numbers... how much do you need, and how much surface area do you need to collect it?

Unfortunately you are much further along then I am. The research I did was for proof of concept when I was figuring out if I could make the property work. I've since lost many of the resource links I could have referred you to. I also did not go into depth on filtration.

Hopefully you will find what I've explained above to be useful.