PRACTICALITIES BY ANDREW BRAY
Environmental protection is very much on everyone's mind so being aware of the options for taking care of onboard waste is more important than ever for sailors.
We know that discharging boat head or toilet waste is objectionable in marinas, and that people do sometimes get very sick after bathing in polluted water, or eating shellfish from it. So while we grumble at sewage management regulations, we know it’s for the public good, at least where there are lots of boats, bathers, or nearby oyster farms, for example.
We may be less convinced that nutrients and chemicals in human body waste are a general rather than a local problem, but many boat owners would willingly reduce their own environmental footprint- even spend money – if the measures were practical. Ignoring impractical regulations is all too easy.
Further realities are that untreated waste and even vent vapours can be a significant health risk to crew, that humans have an instinctive disgust for even the smell of it, and that when stored, sewage rapidly generates even more offensive odours that may permeate through otherwise airtight materials. So there are strong reasons why boat owners ignore regulations that require them to do something the rest of humanity goes to great lengths to avoid ‘ ironically, in many instances.
Regulations have largely been framed by EPAs (Environment Protection Agencies)over the past 20 years and most are based at least in theory on a three-zone system.
For a start, there are always at least some Prohibited Discharge areas within which nothing should be discharged, either because of the sensitiveness of the local environment or the large numbers of boats that use it ‘ marinas, small boat harbours, near beaches etc. Within these zones, if the crew can’t use toilets on shore, then boats must retain waste in holding tanks or portable toilets, and discharge only at pump-outs or where otherwise permitted.
Beyond this there are ‘Treated Discharge’ areas in which raw sewage is still prohibited, but where discharge of sterile appropriately treated sewage is acceptable. This second zone logically includes larger harbours and protected waterways, provided discharge is still prohibited within buffer zones around isolated sensitive areas, such as swimmers or aquaculture.
Beyond this are ‘Untreated Discharge’ areas – waters that are well flushed by tides, not heavily occupied, and environmentally probably well able to cope with untreated raw waste in the quantities generated by ordinary private small craft. Again buffer zones may apply around sensitive points.
As boat owners, we need to be aware of our local regulations. Commercial and larger craft often face stiffer regulations, but for smaller craft with limited crew numbers we are usually faced with two broad options.
Portable toilets Many smaller boats carry portable toilets incorporating an in-built holding tank – a ‘Porta Pottie’ or something similar developed primarily for caravans and RVs. These tyCapacity is strictly limited, but the units are not expensive, and are a simple ‘legal’ solution on boats which are only used for short periods by small crews. Not all are intended for salt-water flushing, and some require DIY hold-down systems to be devised.
Generally, if a boat has an installed flushing toilet it will be required to fit a holding tank into which waste can be diverted. Rules differ as to whether any associated overboard discharge valve needs to be lockable, and whether a deck fitting for dockside pump-out is actually required, but if both these are present the system should be acceptable in most jurisdictions. Probably an overboard discharge pump will be needed, and there may also be rules (as in Queensland) for a macerator, either toilet-integrated, or in any overboard discharge line.
Storing waste until it can be legally discharged seems simple, but isn’t. The general public isn’t permitted to work on, let alone design and install the sewage system in their home, but most holding tanks are retro-fitted on a DIY basis. Unsuitable tank and plumbing materials, and poor detail design (including low loops in hoses) often result in undersized, smelly, blockage-prone installations, which after initial disgusting experiences, owners avoid using. Many retro-fitted tanks prove too small because they needed to fit existing spaces, or were the minimum needed by new regulations ‘ 3L per flush (macerating toilet) and between four and seven flushes per person per 24-hour period is a reasonable basis. So a crew of four over a weekend can easily find 100L inadequate, and few boats could store a week’s sewage even if urine goes directly to the tank without flush water. Professional design and installation can avoid DIY mistakes and provide a functional holding tank system, but that doesn’t mean it will be used.
Even in places where inspections ensure most boats have portables or tanks, compliance even within marinas is often extremely poor. As EPAs have found worldwide, the great majority of otherwise law-abiding citizens simply fail to use dockside pump-outs no matter how many they build or how hard they try to ‘educate’ or enforce. Apart from an aversion to handling waste hoses (and paying for the privilege in some places) and the time taken to get to and use them, the process and associated gagging reactions are the antithesis of a pleasant day on the water. Also, apart from holding tanks often being malodorous shipmates, they create an even bigger and more obvious ‘violation’ when discharged, especially from a stationary boat. This is compounded by having ‘untreated-discharge’ areas impractically distant – outside the State’s three-mile limit in some cases.
DIY odour suppression
Moulded thick-walled polyethylene or polypropylene holding tanks are impermeable. But if the contents are untreated, unpleasant odours generated by anaerobic processes may still permeate hoses and become offensive within the boat. Semi-rigid polyethylene Pool chlorine is probably most commonly added to holding tanks, but proprietary products containing ammonium or zinc saltsor formaldehyde are often used in portables. Since chlorine is a natural constituent of sea water, it’s more acceptable disinfectant than say formaldehyde ‘ most EPAs also tolerate chlorine use in boat antifouling bags. However, DIY dosing is hit and miss ‘ too little and the waste is still dangerous and smelly, too much and it could add to environmental damage even if chlorine is the disinfectant.
On-board chemical treatment
Simple on-board chemical treatment was provided for in the US Coastguard’s MSD (Marine Sanitation Device) Classification system 20 years ago, but some EPAs have rejected the idea, perhaps concerned about chemicals such as formaldehyde entering the environment. For example, as far as I’m aware, no treatment system is currently (June 2007) approved for use by small craft in NSW, and previous approvals have been withdrawn. However, this is not the approach everywhere, and in Queensland, for example, several locally developed and some imported ‘Class C’ (Queensland classification) chemical treatment systems are permitted. These are designed to kill over 99% of bacterial pathogens by chemical disinfection with chlorine precisely metered in, so much per flush. The waste can be discharged anywhere outside a Prohibited Area, except within a half mile buffer zone around ‘sensitive’ areas such as swimmers or aquaculture. These properly engineered on-board treatment systems sterilise sewage so it can be stored inoffensively and legally discharged without visiting a dockside pumpout, or going offshore. They are nearly ‘off-the-shelf’, requiring a minimum of customised plumbing to install, are reasonably compact, not too expensive, and offer a workable solution to the present compliance impasse, even given that some may occasionally malfunction and require maintenance.
On-board tertiary treatment
Internationally, on-board systems to treat black (and grey) water in ships are well developed, and the technologies are now being scaled down to larger small craft. These generally produce a colourless, sterile, low nutrient liquid, equivalent to the tertiary treatment that country towns use before discharging their effluent into rivers. They are flow-through systems, requiring the waste to remain under treatment for some hours at least, but inlet or outlet holding tanks can be added to provide additional surge capacity.
Some use just biological agents in a single stage process, (e.g. Fast-LX series www.marinefast.com), while others are multi-stage processes using either chemicals alone (for example,.Aqua Viro which generates ozone from the water www.aquaviro.com.au ) or a combination of aerobic bacteria and chemicals (for example, Aqua Mare www.nwsa.com.au). Tertiary systems start at around $5k, but are currently too bulky and power-hungry for smaller sailing yachts. With some, there may also be issues with heeling and intermittent use, but as technology improves and demand grows this should change.
Other technological refinements are already possible, such Aqua Viro’s automatic SMS messaging for pump-out services, and GPS integration, so that it won’t discharge within Prohibited Discharge areas. In Queensland, these ‘Class A’ systems can be discharged anywhere outside of Prohibited Discharge areas and, as a bonus, their output should be suitable for re-use on board as toilet flushing water, for example.
An important detail of Queensland’s regulations is that all waste, whether treated or discharged raw, must be macerated. Macerators are essentially blenders which convert toilet paper and waste to a thin slurry that is easier to pump and less likely to block up. The smaller particle size, however, also increases surface area, allowing chemical and biological reactions to occur more rapidly. This advantage also applies when untreated waste is discharged, and the visual results are less offensive and more quickly dispersed, especially if the boat is under way. This advantage is not exploited in places such as NSW where overboard discharge of even treated waste is effectively banned, but untreated waste is in fact routinely discharged by most boats.
While certainly not a mainstream option, compact versions of flush-less so called ‘composting toilets’ intended for caravans have been successfully deployed on boats. Electrical power is needed to evaporate the liquids, with the 12 Volt Sun-Mar mobile unit, for example (www.sun-mar.com ), requiring about 80 Watts on average. This would be difficult to generate on an actively sailing yacht, but might be a viable option where shore power is available, or with an appropriate investment in solar panels for liveaboards. Some RV models drain most of the urine into a container for later separate disposal which reduces the power drain considerably, but might require an additional pump if installed on a boat.
Beyond the brief endurance of crossed legs, going to the toilet is not an optional activity. Regulations based on the storage of untreated sewage are seriously flawed from a health perspective, very unpopular, and largely ignored. If EPAs are serious about finding a solution, they should allow and encourage on-board treatment and discharge. This avoids the smells and unpleasantness of dockside pumps outs and health risks from untreated waste in holding tanks, and reduces the incentive to illegally discharge untreated sewage or chemicals such as formaldehyde into the environment. In conjunction with macerators and realistic Untreated Discharge limits, it also makes it easier for boat owners to choose to do their bit, instead of having to turn Nelson’s blind eye on impractical regulations.
Differences in Australian State regulations are a further nonsense, with a Queensland compliant treatment system, for example, creating an illegal discharge anywhere within NSW. States should co-ordinate their legislation so that boat owners (and boat builders) have practical and affordable guidelines to comply with.
Examples of Queensland Class C systems
This system features two close-mounted polyethylene tanks (385x235x360mm overall), one being a 7L reservoir of swimming pool ‘Liquid Chlorine (10% Sodium Hypochlorite) ‘ enough for a number of flushes. A peristaltic pump is triggered when the toilet’s macerator pump runs, adding chemical as the waste enters a 14L ‘kill’ (treatment) tank. When this is full the toilet pump forces the overflow either into a holding tank, or via a diverter valve, directly overboard. It’s a simple system, with just a few LEDs and level switches, designed for easy DIY installation, and retails for around $1,600. www.sani-loo.com.au
Auto-San (www.bla.com.au) is a similar device.
This system creates its own disinfectant, using electrolysis to generate chlorine from salts already in sea water, with prices starting at around $2,200. The chlorine reacts with water to form hypochlorous acid, which is metered into the waste stream from the toilet as it enters the holding tank. This firm also offers a version (Aqua-San_II) in which the treatment occurs in an intermediate kill tank, prior to flowing through for overboard discharge, or into the holding tank. This might also suit retro fitting to an existing holding tank system, but tanks from 60 to 125L are available as standard. The electrolysis circuit draws about 1.3 Amps at 12 Volts, and initially needs to run for about 12 hours to build up the chlorine concentration in the 7L acid tank. Thereafter, it runs for about 35 minutes per flush, or every four hours if the toilet isn’t being used, to keep up the chemical concentration. This probably involves an average draw of around 200 mA, which even a small solar panel could keep up with.