Hi,
I have been running a solar water heating innovation company in UK for a decade. Having started my career as an aquatic biologist, I have been looking at Legionella in depth. One issue is solar hot water storage, and I hope this post is interesting to an international audience.
In UK, the solar water heating industry is not actually complying with government safety guidance on Legionella and a major shakeup of the solar heating industry is happening right now.
Technically, this guidance (UK HSE Legionella code and guidance L8 para 158), contains a "pack of four", which is:
1 Heat stored water to 60C (140F)
2 Heat it daily
3 Hold it at 60C for 1 hr
4 Heat the whole calorifier contents, including to the base.
Looking at point 4: the "whole contents to the base" requirement, it seems that many in the UK solar thermal industry may be noncompliant because of today's practice of heating part-way down the cylinder only.
From an insurance perspective, the majority of non-domestic solar thermal installations (plus certain domestic ones, such as those in rented and social homes - where L8 applies) may be regarded as noncompliant, and therefore as defective. The fact is that clients are normally within their rights to require all defects (ie faults) to be fixed - free of charge. But this could cost installers £200-£600 ($300-$900) per job. This potential liability (on top of the health and safety one to the user) worries of some major players in the industry and has caused some of them to be overtly hostile to a minority who seek to discuss this issue openly.
My having queried the para 158 noncompliance, and as part of a UK industry group meeting on the subject, the author of L8, Dr Tom Makin (full contact details and references are also available), wrote a report (you will find it on the UK Water Regulations and Advisory Service (WRAS) website) describing conventional solar thermal installations as being "highly likely" to be "creating a risk".
We were not included in this meeting, despite having been given assurances that we would be - and the report was kept secret. However we eventually obtained a copy of this report (under Freedom of Information law). Following our disclosure of this report on our website (as one is permitted to do) some months later it was published on the WRAS website.
I understand that outside Europe there have been cases of Legionella linked to solar thermal. As a company director I am obliged by law to comply with guidance - unless I can explain clearly why I should not. L8 is not a forgotten document: it is regularly used in prosecutions.
Recent evidence of successful L8 proescutions or censure of UK government agencies:
£24,000 ($36,000) fine plus costs: Welsh care home for inadequate legionella assessments
http://www.hse.gov.uk/press/2009/coiw37209.htm £25,000 ($37,000) fine plus costs: butchers / meat packers.
http://www.hse.gov.uk/PRESS/2009/coinw01109.htm £300,000 fine ($450,000) plus costs: Cider maker HP Bulmer Limited
http://www.hse.gov.uk/PRESS/2008/wm421708.htm £48,000 fine ($72,000) plus costs: Liverpool hospital. Unsafe levels of legionella in water for showers, etc.
http://www.hse.gov.uk/PRESS/2009/coinw036trust09.htm Even the prison service has infected prisoners
http://www.hse.gov.uk/Prosecutions/documents/crowncensures.htm There is more detail on the solartwin.com website.
I hope this is interesting. I can send readers papers if they want.
Regards, Barry.