| |
- Downpours beaten
- Lead law' update
- Reality check
- On the hunt
- Health check
- Survey results
- Fire goes green
- Double dipping
- Flow reduction
- UK farming misery
- Bugs eating through fat
- 'Super' solution
- Luxury goes green
- O2 overcomes, too
- Norway shows the way
- Dubai: Changing landscape
- Harsh environment
- Democracy brings water
- Government leads the way
- Extracting oil from stand
- Heat Pumps: The new era
- Sao Paulo's hotel unique
- Masquerading dummies
- Testing times 'down-under'
- iFlush: The digital revolution
- Much more to good design
- New lead policy
- India's modern sanitation
- Fire suppression systems
- From Hutong to high-rise
- Attracting woman engineers
- Contemplating the future
|
|
Time for a gravity system redesign?
The most common plumbing system
design in the eveloped world is
based on the hydraulic performance
of gravity – a system fundamentally unchanged
since the 19th century.
However, as global water and plumbing
industries are discovering, there is clear
evidence that the system is showing signs of
stress due to big reductions in drainage flow.
Global warming concerns and water shortages
create problems of their own. These problems
are compounded by government water-saving
strategies, together with more recent moves to
reduce plumbing costs, such as reducing the
venting requirements and changing the design of
drainage connections.
In Australia, lower drainage flows have been
brought about by reducing water use to counter
the effects of enduring drought. Such reductions
also compensate for a lack of investment in
water infrastructure to meet the demands of
growing cities.
The focus has remained on reducing the
performance of various fixtures (toilets, taps,
showers, etc), with insufficient consideration
given to the effect on the overall system.
A salient example of the importance of
matched plumbing design is the Hong Kong
SARS epidemic, which brought about big
design changes in plumbing. The 2003 report
by the World Health Organisation (WHO) found
inadequate plumbing to be the most likely
contributor to the spread of SARS in residential
buildings – as well as several other infectious
diseases around the world.
The push to improve the water efficiency of
household appliances and plumbing fixtures has
brought about substantial reductions in water
use in most Australian cities, attracting the
interest of many other countries.
Australia is committed to even greater water
savings for toilets, taps and other point-of-use
fixtures. However, a study is urgently required to
investigate the influence of toilet flush volumes
of less than 4.5/3L (1.2/0.8 US gallons) on
existing drainline systems complying with the
AS/NZS 3500 Standard.
The increasing increasing? uptake of
graywater and blackwater recycling systems has
further affected drain lines by compromising
engineered drainage systems in dwellings and
commercial buildings.
Some Australian States have proposed
amending building codes to allow for separate
graywater and blackwater drainage systems in
dwellings, a notion that has rung some alarm
bells.
In Australia, New Zealand and many other
countries there is little evidence of adequate
research and testing to confirm the long-term
effect of such changes.
In the latter half of 2007, the Australian
and New Zealand Plumbing Regulators Forum
(NPRF) met to consider the issue, and it agreed
to develop a study program for which funding
would be obtained.
The project – Scientific Review of Reduction
of Flows on Plumbing and Drainage Systems in Australia and New Zealand – is in the process of
finalising the briefing paper.
NPRF technical committee chairman Jeffrey
Clark, who represents the South Australian
Water Corporation, believes that some
intervention is justified.
“We are concerned that if flushing volumes
for toilets are further reduced, there could be
implications for our internal plumbing systems
as well as external infrastructure. This would
affect the way Australian Standards are written – they would need to be substantially changed.”
Clark doesn’t think we have gone too far in
our attempts to save water but he believes trials
are justified to ascertain to what extent the
reduction adversely affects plumbing.
“In South Australia we’ve had issues
with commercial plumbing systems causing
blockages. We’ve also had issues with waterless
urinals and other such systems. We have made
some changes in the current amendments to
AS/NZS 3500 to better protect the drainage
system.”
The main problem with urinals that do not
use water is the build-up of uric acid, which
blocks the urinal trap and drain pipe. Note:
Roger van Gelder (rogervangelder@aol.com)
has done some investigation re: waterless
urinals at the University of Washington (N.W.
U.S.A.) and found that a ‘“sludge’” builds up
in both the horizontal and vertical legs of the
drain pipe behind the urinal. The sludge has not
been analysed yet to determine exactly what it
contains but Roger mentionedthe investigation
found that it seems to contains hair, dust, skin
flakes, etc. John and I have seen it and it is
pretty disgusting! His drain pipes were between
1/3 and 2/3 blocked after six6 months (new
drain pipes were originally installed).
Clark says the industry, in conjunction with
the NPRF technical committee, has been
conducting long-term trials in the performance
of waterless urinals.
“Without water flushing the drain, the waste
line will eventually block up. From what has been
observed to this time, the discharge pipe is
two-thirds blocked. Note: the word “already” is
ambiguous, i.e., does “already” mean 6 months
into a 2-year study, or was the drain pipe twothirds
blocked on the first day? So we need to
review the Standards to deal with the need for
better overall design. This could mean running
fixtures past the urinal first, instead of having
them on dead legs or dead branches.”
Some of the long-term effects of problem
drains are being experienced, with home-owners
calling plumbers out to rectify drainage system
blockages that cause odors inside buildings.
Plumbing regulators are dedicated to
conserving water. However, Clark and other
regulators also want to ensure that plumbing
systems are not causing blockages that can lead
to overflows and adversely affect public health
and the environment.
Trials are taking place in Perth, Western
Australia, and Canberra, the national capital.
The continuation of such trials is essential to the
overall outcome of the project.
Caroma, Australia’s main supplier of
plumbing? fixtures, fully supports the project
because the design of fixtures must be
performance matched with the plumbing
system.
The technical committee aims to have all
trials completed in the next 18 months.
Caroma’s research and development manager
Dr Steve Cummings has been researching
other plumbing? drainage? models to compare
overseas practices with Australian practices. He
says future problems stemming from reduced
flows won’t be isolated to Australia.
Germany in particular has reduced its flow
rates and water consumption to almost half the
level of a typical Australian dwelling.
There is concern among the general
community in the United Kingdom regarding
government water containment. Waterwise UK
head of research Joanne Zygmunt says sewers in
many places have to be flushed with substantial
amounts of water because flows from dwellings
are insufficient.
“The average per capita consumption of
water in the UK is about 148L (39 US gallons)
a day. If this goes down to as low as 100L (26
US gallons), problems may be experienced. The
government vision for new homes is about 110L
(29 US gallons) per person per day.”
“In the past the UK could rely on the generally Australia and New Zealand – is in the process of
finalising the briefing paper.
NPRF technical committee chairman Jeffrey
Clark, who represents the South Australian
Water Corporation, believes that some
intervention is justified.
“We are concerned that if flushing volumes
for toilets are further reduced, there could be
implications for our internal plumbing systems
as well as external infrastructure. This would
affect the way Australian Standards are written – they would need to be substantially changed.”
Clark doesn’t think we have gone too far in
our attempts to save water but he believes trials
are justified to ascertain to what extent the
reduction adversely affects plumbing.
“In South Australia we’ve had issues
with commercial plumbing systems causing
blockages. We’ve also had issues with waterless
urinals and other such systems. We have made
some changes in the current amendments to
AS/NZS 3500 to better protect the drainage
system.”
The main problem with urinals that do not
use water is the build-up of uric acid, which
blocks the urinal trap and drain pipe. Note:
Roger van Gelder (rogervangelder@aol.com)
has done some investigation re: waterless
urinals at the University of Washington (N.W.
U.S.A.) and found that a ‘“sludge’” builds up
in both the horizontal and vertical legs of the
drain pipe behind the urinal. The sludge has not
been analysed yet to determine exactly what it
contains but Roger mentionedthe investigation
found that it seems to contains hair, dust, skin
flakes, etc. John and I have seen it and it is
pretty disgusting! His drain pipes were between
1/3 and 2/3 blocked after six6 months (new
drain pipes were originally installed).
Clark says the industry, in conjunction with
the NPRF technical committee, has been
conducting long-term trials in the performance
of waterless urinals.
“Without water flushing the drain, the waste
line will eventually block up. From what has been
observed to this time, the discharge pipe is
two-thirds blocked. Note: the word “already” is
ambiguous, i.e., does “already” mean 6 months
into a 2-year study, or was the drain pipe twothirds
blocked on the first day? So we need to
review the Standards to deal with the need for
better overall design. This could mean running
fixtures past the urinal first, instead of having
them on dead legs or dead branches.”
Some of the long-term effects of problem
drains are being experienced, with home-owners
calling plumbers out to rectify drainage system
blockages that cause odors inside buildings.
Plumbing regulators are dedicated to
conserving water. However, Clark and other
regulators also want to ensure that plumbing
systems are not causing blockages that can lead
to overflows and adversely affect public health
and the environment.
Trials are taking place in Perth, Western
Australia, and Canberra, the national capital.
The continuation of such trials is essential to the
overall outcome of the project.
Caroma, Australia’s main supplier of
plumbing? fixtures, fully supports the project
because the design of fixtures must be
performance matched with the plumbing
system.
The technical committee aims to have all
trials completed in the next 18 months.
Caroma’s research and development manager
Dr Steve Cummings has been researching
other plumbing? drainage? models to compare
overseas practices with Australian practices. He
says future problems stemming from reduced
flows won’t be isolated to Australia.
Germany in particular has reduced its flow
rates and water consumption to almost half the
level of a typical Australian dwelling.
There is concern among the general
community in the United Kingdom regarding
government water containment. Waterwise UK
head of research Joanne Zygmunt says sewers in
many places have to be flushed with substantial
amounts of water because flows from dwellings
are insufficient.
“The average per capita consumption of
water in the UK is about 148L (39 US gallons)
a day. If this goes down to as low as 100L (26
US gallons), problems may be experienced. The
government vision for new homes is about 110L
(29 US gallons) per person per day.”
Question: are the sewers in the UK typically
combined (i.e., is the same sewer used for
sanitary as well as storm water)? Based on
the following few sentences, should you say, “In the past the UK could rely on the generally dependable rainfall to allay any such concerns.”
However, Waterwise director Jacob Tomkins
concedes that water scarcity is a real concern.“In reality the UK has less available water per
person than most other European countries, and
the Thames Valley is technically classified as
semi-arid,” he says.
“Climate change is making this worse as
rainfall becomes less regular and more intense,
leading to floods and droughts. At the same time
the UK is experiencing a population shift to the
driest parts of the country, and households are
smaller but with higher consumption.”
In the past two years southern England has
had the worst droughts and the worst floods
for a century, both of which resulted in water
shortages.
“This is not just a southern England problem– there was a drought in Dundee in north-east
Scotland a couple of years ago. The Government
is responding to these issues by developing new
legislation to promote water-efficient housing
and bathroom fittings, with the aim of reducing
per capita consumption from 150L (40 US
gallons) to 120L (32 US gallons) per day.”
Tomkins also says low-flow studies have been
inconclusive.
“There is some concern that reduced flow will
result in sewer blockages. However, it generally
seems that the problem stems from poor sewer
design and maintenance, and the flushing of
non-sewerage items.”
The UK Environment Agency is due to release
a report titled Less Water to Waste: The Effects
of Water Efficiency on Wastewater Flows. It is
hoped it will shed light on water conservation
methods and their effect on infrastructure.
Yet it is clear that the UK is still lagging behind
Australia. The NPRF findings should provide
a telling prognosis and allow the Australian
plumbing industry to more effectively combat
water shortages (and global warming in the
longer term) and curb any initiatives that are
being taken too far.
It may be possible to take a leaf out of Veritec
Consulting principal Bill Gauley’s book. Since
2003, Gauley has been conducting tests in North
America on flush performance, known as MaP
testing (maximum performance of toilet fixtures).
In the US and Canada it seems that the 6L
systems are more than sufficient. In 2006 WPR
spoke to Gauley, who uses soybean paste (with
similar properties to human waste) to test the
efficiency of certain toilet models and their
capacity to flush.
“Based on the results of extensive
performance testing, manufacturers stepped up
to the plate and began making far better toilets,”
he says.
“While the minimum threshold for providing
customer performance satisfaction is set
at 250g (0.6 pounds), some models today
can flush over 1,000g (2.2 pounds) and be
classified as truly exceptional.”
Tests by Gauley are ongoing – and required– as North America moves towards blanket
manufacture of ‘ (actually HETs have “effective’”
flush volumes of 4.8L (or 1.28G). As drought
hits harder and initiatives to curtail water use
become more prevalent, MaP testing takes on
greater importance.
Gauley has also completed a series of tests to
determine just how far low flush volume toilets
can transport waste through the drain pipe. His
research has found that while toilet flush rate
is an important factor, flush volume is by far
the most important aspect concerning drainline
carry distance. Gauley says, “If we intend to
use toilets flushing with less than about three
litres of water in our homes we may have to
redesign our drainage systems, e.g., steeper
slopes, smaller diameter piping, and perhaps
less intrusive couplings”. He strongly agrees
that more research must be done to assess the
effects of lower flow rates in our drain systems.
“One outcome may be,” he says, “that
we allow lower flush volumes for residential
installations where supplemental flows from
showers, baths, and clothes washers help
transport waste to the sewer and higher flush
volumes for commercial installations where drain
pipes have larger diameters, flatter slopes, and
little or no supplemental flows.”
Australia is well ahead of North America in its
plans to conserve water: WELS Standards are
compulsory, whereas Uniform North American
Requirements (UNAR) is a voluntary program.
Yet, we should take heed of Gauley’s tests and
monitor them closely as the capacity of toilet
systems in North America continues to be
reduced.
The possibility of blockages, pungent odours
and drain damage doesn’t bode well for future
water reductions, yet the results of test trials
are still at least 18 months away and it would
be prudent of any agency thinking about
reductions to rethink its stance until all the
evidence is in.
|
|
