they are slightly larger than a flush toilet, but use roughly the same floor space. some units use fans for aeration, and optionally, heating elements to maintain optimum temperatures to hasten the composting process and to evaporate urine and other moisture. operators of composting toilets commonly add a small amount of absorbent carbon material (such as untreated sawdust, coconut coir, or peat moss) after each use to create air pockets to encourage aerobic processing, to absorb liquid and to create an odor barrier. this additive is sometimes referred to as "bulking agent". some owner-operators use microbial "starter" cultures to ensure composting bacteria are in the process, although this is not critical. vermifilter toilet a vermifilter toilet is a composting toilet with flushing water where earthworms are used to promote decomposition to compost. it can be connected to a low-flush or a micro-flush toilet which uses about 500 millilitres (17 us fl oz) per use. solids accumulate on the surface of the filter bed while liquid drains through the filter medium and is discharged from the reactor. the solids (feces and toilet paper) are aerobically digested by aerobic bacteria and composting earthworms into castings (humus), thereby significantly reducing the volume of organic material. other some units employ roll-away containers fitted with aerators, while others use sloped-bottom tanks. maintenance maintenance is critical to ensure proper operation, including odor prevention. maintenance tasks include: cleaning, servicing technical components such as fans and removal of compost, leachate and urine. urine removal is only required for those types of composting toilets using urine diversion. once composting is complete (or earlier), the compost must be removed from the unit. how often this occurs is a function of container size, usage and composting conditions, such as temperature. active, hot composting may require months, while passive, cold composting may require years. properly managed units yield output volumes of about 10% of inputs. uses of compost finished compost from a composting toilet ready for application as soil improvement in kiel-hassee, germany main articles: uses of compost and reuse of excreta the material from composting toilets is a humus-like material, which can be suitable as a soil amendment for agriculture. compost from residential composting toilets can be used in domestic gardens, and this is the main such use. enriching soil with compost adds substantial nitrogen, phosphorus, potassium, carbon and calcium. in this regard compost is equivalent to many fertilizers and manures purchased in garden stores. compost from composting toilets has a higher nutrient availability than the dried feces that result from a urine-diverting dry toilet. urine is typically present, although some is lost via leaching and evaporation. urine can contain up to 90 percent of the residual nitrogen, up to 50 percent of the phosphorus, and up to 70 percent of the potassium. compost derived from these toilets has in principle the same uses as compost derived from other organic waste products, such as sewage sludge or municipal organic waste. however, users of waste-derived compost must consider the risk of pathogens. pharmaceutical residues waste-derived compost may contain prescription pharmaceuticals. such residues are also present in conventional sewage treatment effluent. this could contaminate groundwater. among the medications that have been found in groundwater in recent years are antibiotics, antidepressants, blood thinners, ace inhibitors, calcium-channel blockers, digoxin, estrogen, progesterone, testosterone, ibuprofen, caffeine, carbamazepine, fibrates and cholesterol-reducing medications. between 30% and 95% of pharmaceuticals medications are excreted by the human body. medications that are lipophilic (dissolved in fats) are more likely to reach groundwater by leaching from fecal wastes. sewage treatment plants remove an average of 60% of these medications. the percentage of medications degraded during composting of waste has not yet been reported. history further information: dry toilet § history in the late 19th century in developed countries, some inventors, scientists and public health officials supported the use of "dry earth closets", a type of dry toilet with similarities to composting toilets, although the collection vessel for the human waste was not designed to compost. society and culture regulations international organization for standardization (iso) in 2016, the international organization for standardization (iso) published the standard "activities relating to drinking water and wastewater services — guidelines for the management of basic on-site domestic wastewater services". the standard is meant to be used in conjunction with iso 24511. it deals with toilets (including composting toilets) and toilet waste. the guidelines are applicable to basic wastewater systems and include the complete domestic wastewater cycle, such as planning, usability, operation and maintenance, disposal, reuse and health. international association of plumbing and mechanical officials the international association of plumbing and mechanical officials (iapmo) is a plumbing and mechanical code structure adopted by many developed countries. it recently proposed an addition to its "green plumbing mechanical code supplement" that, "...outlines performance criteria for site built composting toilets with and without urine diversion and manufactured composting toilets." if adopted, this composting and urine diversion toilet code (the first of its kind in the united states) will appear in the 2015 edition of the green supplement to the uniform plumbing code. united states no performance standards for composting toilets are universally accepted in the us. seven jurisdictions in north america use american national standard/nsf international standard ansi/nsf 41-1998: non-liquid saturated treatment systems. an updated version was published in 2011. systems might also be listed with the canadian standards association, cetl-us, and other standards programs. regarding byproduct regulation, several us states permit disposal of solids from composting toilets (usually a distinction between different types of dry toilets is not made) by burial, with varying or no minimum depth mandates (as little as 6 inches). for instance: massachusetts: "residuals from the composting toilet system must be buried on-site and covered with a minimum of six inches of clean compacted soil. massachusetts requires that any liquids produced but, "not recycled through the toilet either discharged through a greywater system on the property that includes a septic tank and soil absorption system, or removed by a licensed septage hauler." oregon: "humus from composting toilets may be used around ornamental shrubs, flowers, trees, or fruit trees and shall be buried under at least twelve inches of soil cover." rhode island: "solids produced by alternative toilets may be buried on site," while, "residuals shall not be applied to food crops." virginia: "all materials removed from a composting privy shall be buried," and "compost material shall not be placed in vegetable gardens or on the ground surface." vermont: "byproducts may be disposed via "...shallow burial in a location approved by the agency that meets the minimum site conditions ." washington: models its extensive regulations for what it refers to as "waterless toilets" on the federal regulations that govern sewage sludge. the environmental protection agency has no jurisdiction over the byproducts of a dry toilet as long as waste are not referred to as "fertilizer" (but instead simply a material that is being disposed of). federal rule 503, known colloquially as the "epa biosolids rule" or the "epa sludge rule" applies only to fertilizer. thus, individual states regulate composting toilets. germany the regulations for composting toilets and other forms of dry toilets in germany vary from state to state and from one application to another (e.g. use in allotment gardens or use in family homes and settlements). in the different states of germany, it is the "landesbauordnung" (translates to "state civil engineering regulations") of the respective state that regulates the use of such alternative toilets. most of them stipulate the use of flush toilets, however there are many exceptions, for example in the states of hamburg, lower saxony, bavaria, mecklenburg-western pomerania, rhineland-palatinate, saxony-anhalt and thuringia. these generally make exceptions for the use of composting toilets in homes provided that there are no concerns for public health. regulations governing the use of compost and urine from composting toilets is less clear in germany but it seems generally allowed provided it is used on one's own property and not sold to third parties. examples finland numerous sparsely settled villages in rural areas in finland are not connected to municipal water supply or sewer networks, requiring homeowners to operate their own systems. individual private wells, i.e. shallow dug wells or boreholes in the bedrock, are often used for water supply, and many homeowners have opted for composting toilets. in addition, these toilets are common at holiday homes, often located near sensitive water bodies. for these reasons, many manufacturers of composting toilets are based in finland, including biolan, ekolet, kekkilä, pikkuvihreä and raita environment. estimates made by leading finnish composting toilet manufacturers and the global dry toilet association of finland provided the following 2014 figures for composting toilet use in finland: about 4% of single-family homes not connected to a public sewer network are equipped with a composting toilet. some 200,000 manufactured composting toilets are thought to serve holiday homes, matched by the number of other dry toilets. the simplest ones are sited in an outhouse. germany composting container of "terranova" composting toilet, showing open removal chamber (town house at the ecological settlement hamburg-allermöhe, germany) composting toilets have been successfully installed in houses with up to four floors. an estimate from 2008 put the number of composting toilets in households in germany at 500. most of these residences are also connected to a sewer system; the composting toilet was not installed due to a lack of sewer system but for other reasons, mainly because of an "ecological mindset" of the owners. in germany and austria, composting toilets and other types of dry toilets have been installed in single and multi-family houses (e.g. hamburg, freiburg, berlin), ecological settlements (e.g. hamburg-allermöhe, hamburg-braamwisch, kiel-hassee, bielefeld-waldquelle, wien-gänserndorf) and in public buildings (e.g. ökohaus rostock, vhs-ökostation stuttgart-wartberg, public toilets in recreational areas, restaurants and huts in the alps, house boats and forest kindergartens). the ecological settlement in hamburg-allermöhe has had composting toilets since 1982. the settlement of 36 single-family houses with approximately 140 inhabitants uses composting toilets, rainwater harvesting and constructed wetlands. composting toilets save about 40 litres of water per capita per day compared to a conventional flush toilet (10 liter per flush), which adds up to 2,044 m³ water savings per year for the whole settlement. united states slow composting toilets have been installed by the green mountain club in vermont's woodlands. they employ multiple vaults (called cribs) and a movable building. when one of the vaults fills, the building is moved over an empty vault. the full vault is left untouched for as long as possible (up to three years) before it is emptied. the large surface area and exposure to air currents can cause the pile to dry out. to counteract this, signs instruct users to urinate in the toilet. the club also uses pit latrines and simple bucket toilets with woodchips and external composting and directs users to urinate in the forest to prevent odiferous anaerobic conditions. worldwide composting toilets with a large composting container (of the type clivus multrum and derivations of it) are popular in us, canada, australia, new zealand and sweden. they can be bought and installed as commercial products, as designs for self builders or as "design derivatives" which are marketed under various names. it has been estimated that approximately 10,000 such toilets might be in use worldwide.