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Frequently asked questions:

1. Q. Why should I have a composting toilet?

A.

No smell, no splash, and a silent 'flush'. For sites without existing foul drainage. For sites with drainage problems such as clayey soil and a consequent need to reduce the volume of waste water. Where water supply is unavailable or unreliable. From a desire to reduce water consumption for cost or environmental reasons. To eliminate frost or flooding risk in unheated buildings. From a desire to recycle organic wastes and to avoid the requirement to have sewage sludge removed by tanker.



2. Q. Will a NatSol composting toilet smell?

A. No. In customer surveys no respondents have reported odour problems.



3. Q. How is the toilet ventilated?

A. Ventilation takes place down the toilet pedestal which removes odours at source. Consequently, our toilet cubicles can be expected to smell less than WC cubicles. Most of our toilets are passively vented but a fan option is available for installation in multi-purpose buildings.



4. Q. Can compost toilets fit in the space taken by a WC?

A. NatSol is not aware of any genuine composting toilet which fits in the space taken up by a WC. There are some toilets which are not much larger but these are usually incinerating or dehydrating toilets or "bucket" toilets. The critical dimension in most situations is not the floor area taken up by a composting toilet but the space required below the floor. In particular, the depth of vault required. NatSol toilets can be constructed with as little as 750mm vault depth and because there is no requirement with an NatSol toilet for drainage from the bottom of the vault it is possible for the vault to extend below ground level.



5. Q. Why urine separation?

A. Urine separation diverts the urine from a seated user and away from the compost pile to a soakaway or collection tank. Removing the urine means that the vault contents are drier and that the vault does not require drainage. This is a very considerable advantage over other types of toilet. Furthermore, exclusion of urine from the vault reduces the likelihood of smells. NatSol toilets need very little soak material because of urine separation. A ceramic wall mounted urinal is usually provided for men.



6. Q. Why not get rid of the urine by evaporation?

A. In the relatively cool and wet UK climate getting rid of urine by evaporation is likely to be very unreliable. Other reasons are [i] that wet systems can be more prone to infection with certain species of insect such as drone flies and [ii] that by using a urine soakaway some of the useful nutrients can be made use of by plants.



7. Q. Why does the COMPUS TWIN have two vaults?

A. The two vaults provide a batch processing system. One vault is in use whilst the other rests so that when compost is removed even the newest deposit has had a whole year to decompose. Systems which use a single vault rely on the height and gradient of the vault to separate fresh wastes from older wastes but this doesn't give good separation.



8. Q. How many people can use a COMPUS TWIN FULL ACCESS?

A. It depends on the situation. If used as the only toilet by people living on site then typically up to 10 people. For daytime use, e.g. on allotment sites, up to 100 uses per day. Intermittent peak loadings can be much higher.



9. Q. Is it possible to have a single vault NatSol toilet?

A. NatSol has developed some single chamber designs. Whilst twin vault toilets have many advantages there are situations where single chamber designs may be more appropriate. The COMPUS COMPACT is suitable for low use private situations.



10. Q. Do the toilet buildings come supplied with a light?

A. A light could be fitted, running from a photovoltaic panel or a mains supply, but NatSol does not supply cubicle lights.



11. Q. Why is the pedestal the shape that it is?

A. Good design requires that form follows function. A WC pan is shaped as it is to make flushing possible. In an unflushed toilet it is important to shape the pedestal to avoid fouling the inner surfaces. We normally manufacture the pedestal in grey externally because most of our installations are on remote work sites and this does not show marks readily. The internal surface is black which absorbs light and reduces visibility of the vault contents.



12. Q. Are flies a problem with composting toilets?

A. We would be suspicious of any manufacturer of a genuine composting toilet who claimed they had never had flies in one of their composting toilets. There are a large number of dung fly species in the UK and due to their small size they can fairly easily find their way into a toilet vault. However, we are pleased to report that a recent survey of our toilets did not reveal any problems with flies. Our research has also demonstrated that should they occur the problem can be resolved by a change in the management regime. The most likely cause is due to high moisture content in the vault and this may be caused by failure to clean the urine separating system. To a large extent fly larvae will be eaten by other small predators in the compost pile. However, we cannot completely guarantee fly free performance due to the complex nature of composting processes. Dung flies are not likely to act as disease vectors because they are not usually attracted to food.



13. Q. Does it take much time to manage a NatSol compost toilet?

A. Really very little, but it is important to remember to check certain things on a regular basis. A set of management instructions will be provided with every installation.



14. Q. How is the finished compost emptied and what can be done with it?

A. For our "in-ground" toilets we supply a custom made shovel for emptying the compost through one of the front floor hatches. If the management instructions have been followed and if the resting vault has been left for a minimum one year period the compost should be odourless, friable and pleasant enough to remove. You should not assume, however, that it is completely pathogen free and we recommend further composting outside of the toilet. Some human parasite eggs survive for longer and for this reason we advise against the use of compost on food crops. Further instructions about the use of compost will be provided if you purchase a NatSol toilet.



15. Q. What are the vaults made from?

A. This depends on your situation. We typically supply preformed GRC vaults to be installed underground. Above ground vaults can also be constructed on site from masonry by your own builder to our specification.

The standard in-ground GRC vaults may not be suitable for high ground water applications but we can supply a special version for such situations. Please enquire.



16. Q. Can composting toilets be made suitable for wheelchair users?

A. Our COMPUS TWIN FULL ACCESS toilet is large enough for wheelchair access under current building regulations. We do not supply an alarm system for these toilets as most go on remote sites without electricity.



17. Q. Do I need planning or building control approval?

A. It is often necessary to have planning and building control approval from the local authority before installing composting toilets. Although the responsibility for acquiring these consents rests with you, the client, we are happy to assist in acquiring them and have considerable experience in so doing. No local authority has so far refused.

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