Re: Distance between Septic Tanks and Water Wells


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  • F H Mughal
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Distance between Septic Tanks and Water Wells

Distance between Septic Tanks and Water Wells

Attached is the USEPA publication titled: “Drinking Water From Household Wells.” While the title of the publication pertains to water, pp. 14 of the document gives distances between wells and septic tanks and other structures. The distances are:

Septic Tanks 50 feet
Livestock Yards, Silos Septic
and Leach Fields 50 feet
Petroleum Tanks, Liquid-tight Manure Storage,
Pesticide and Fertilizer Storage and Handling 100 feet
Manure Stacks 250 feet

As can be seen from above, distance-wise, septic tanks have been bracketed with livestock yards and leaching fields, while the distance increase to 250 ft for manure stacks.

I was expecting a larger distance (250 ft) for the septic tanks. The lower distance of 50 ft could be due to the fact that, in US, the construction standards are strict, and the workmanship is of high quality. That is why USEPA recommends a distance of 50 ft between septic tanks and wells.

F H Mughal
F H Mughal (Mr.)
Karachi, Pakistan

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  • hajo
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Re: Distance between Septic Tanks and Water Wells

Dear Mughal,

unfortunately keeping GW clear of septic tanks is not as easy as this EPA paper wants make us believe - and it is also a bit outdated, Jan. 2002.

We have newer and better information available if we scan the Forum:
one of our specialists on the forum seems to be 'kanalwolf', if you enter this user name in the search you find access to a number of information regarding this topic.

One of the search results refers you to recent publication (2015) on the Forum
which surely provides newer and more accurate information (copy attached).

I know in the field we often have not all information available which are required to take the correct decision when siting a septic tank/pit latrine or water source (well?) but the 50 feet in this paper seems to me so ridiculous small that I felt warning readers to work with it.

... also the term 'well' may be understood in different ways: for me and many others a 'well' is a hand-dug water source of max 15-25m depth thus drawing from surface close 'underground' water, which is why these 'wells' do not always provide potable water and are more vulnerable to contamination by close-by sanitation infrastructure. I guess the EPA paper by 'well' means 'drilled boreholes' which go deeper (~100m), draw from lower aquifers and therefore provide better quality. Especially with a sanitary seal they are not so prone to contamination by surface (close) water, but also for them it depends on the circumstances (see publication) of GW flow direction and underground geology.

... and I think the 50 ft in the EPA paper should not have any relation to presumably high construction standards in the US. A septic tank is supposed to have a leach field around where the effluent is percolated into the underground and hopefully cleaned by soil and micro-organism in the ground before it reaches the GW level. For this purpose the distance, soil condition, GW flow between septic tank and GW matters not the quality of structure, I presume. Anyway, I feel 50 ft is much too close even to work as a 'rule of thumb'.

ciao, Hajo
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