Dave Miller provides the answers to the questions he hears most often:

Q: How do I decide which wastewater system is right for me

A: With new treatment plants appearing on the market and glossy brochures arriving in your mailbox, it is not easy to decide which system is best for your requirements. Ringing your local plumber or tank manufacturer may not give you the best answer as many of them act as agents for particular systems and do not give independent or professional advice. An independent environmental engineer can investigate the full range of sewage treatment and disposal options available, provide cost estimates for each option and discuss these further to help you select the most appropriate system for your site and requirements. This service will ensure that you get the system that is right for your site and requirements, rather than one that suits the financial requirements of the person who sells it to you.

Q: What happens when we have chosen that most appropriate system for our site and requirements?

A: I can then prepare a full engineering design to council specification for the selected option. I can either manage the project on your behalf or you can handle the purchase and installation yourself.

Q: What type of sewage treatment systems can you design?

A: Given my knowledge and experience, I can design a wide range of disposal systems, including improved septic tank technology, Low Pressure Effluent Disposal (LEPD) Systems and sewage to clearwater systems to meet all Council requirements.

Q: How do you save your clients money?

A: As I am totally independent and do not have any financial interest in any wastewater products, tank manufacturing, installation or associated businesses, I act solely in my client's interest to design the most cost-efficient system for their site. I can choose between all the products and manufacturers available, and if restoring an existing system or buying a smaller system than first considered, is what best suits your site and requirements, then that is what I will recommend.

Q: Do you recommend 'off the shelf' products?

A: Yes, some products in some circumstances. The problem is that there are now so many different products available. A group of environmental engineers attending an international wastewater conference recently concluded that of the 31 'off the shelf' sewage treatment plants currently available, they would recommend only five. Some systems are fine, but as the Master Builders tv adverts say: "There are cowboys out there!"

Q: If you do not have business relationships with manufacturers or suppliers to receive commissions, how do you earn an income?

A: I do not earn a cent from any manufacturer, supplier or installer. I charge my clients a fee for my independent advice service and for preparing engineering designs. I also run seminars for industry professionals and manage wastewater projects on behalf of groups or organisations.

Q: What is a Low Pressure Effluent Dosing (LPED) system?

A: This is a system that collects all the wastewater (sewage) from a house in a filtered septic tank and pumps it into the ground at a precise rate where naturally occurring bacteria complete the treatment process. But the disposal area is effectively acting as a treatment plant and should be fenced off and not used for any other purpose. With today's technology, LPED systems can last for many years and should not have any odour or ponding problems that are sometimes associated with traditional septic tanks. I have prepared a list of suitable trees and shrubs that can be planted over the disposal field to create an attractive bush area.

Q: How sophisticated does a LPED system need to be?

A: This depends on your particular site. Conditions such as the layout of the land, soil type, groundwater levels, environmental sensitivity and council requirements must all be taken into account. If the site is unsuitable for a septic tank (LPED) system, or the owner does not want one, there are a number of treatment plants and processes available that fully or partially treat the sewage before spreading it into the ground. However, some plants are better than others and if the wrong one is selected the owner could be in for a costly and unpleasant experience.

Q: What maintenance costs do septic tanks and sewage treatment systems require?

A: All septic tanks and treatment plants require some form of maintenance, especially if pumps, chemicals and aerators are involved. With an aerated treatment plant this usually involves a regular (six monthly) visit by the agent. After the initial free maintenance checks it becomes the owner's responsibility to organise and pay for this service, without which the treatment plant will inevitably fail. Some systems appear cheaper to buy but could require more frequent and expensive maintenance.

Q: How long should a sewage treatment plant last?

A: There is no simple answer. However, the better the treatment plant design and quality of its components, the longer it will last. There is one treatment process available which has a calculated life of 125 years and another that has presented problems after only a few months. Most aerated systems will offer a guarantee of 15-25 years on the tank, but this can be like having a rust free car body and a blown motor. It is the quality of the design and components that give a good treatment plant its reliability and life expectancy.

Q: Do I need an independent wastewater system design?

A: If you want to be able to make an informed choice on the type and cost of sewage treatment and disposal for your site, the answer is definitely yes. Sewage treatment is not a pleasant subject and if you get it wrong it can be a major expense. My service is designed to help you and to save you money and hassles. If you have any other questions, please feel free to contact me. My reputation is based on quality customer service and helping my clients to make informed choices, which save them money and sewage problems later on.