We’re often sent plans and sketches and asked a simple question:
“Will this pump be suitable for my WC, kitchen or extension?”
It’s an understandable question. But once levels, distances and foul drainage are involved, it stops being product advice and becomes engineering judgement.
Where a layout involves changes in level, long pipe runs, bends, or foul waste, giving informal recommendations is not helpful and it is not responsible. At that point, the question is no longer about choosing a product. It is about whether a system will actually work, long term. That means understanding total head, not just vertical lift. It means accounting for friction losses, pipe diameter, bends, valves, duty cycles and solids handling. Two schemes that look similar on paper can behave very differently once installed.
Making a quick recommendation in those circumstances might feel helpful in the moment, but it can easily store up problems for later.
There is a temptation to give an answer simply because one is being asked. Saying no, and explaining why, can feel awkward. But declining to provide site-specific advice without proper scope is about protecting the customer, not withholding help. Quick reassurance often feels good at the time. Robust engineering usually proves its value later.
Pumps that are undersized may block or lead to flooding. Pumps that are oversized short-cycle and fail early. Systems that are marginal often appear fine at first and then become maintenance problems months or years later.
Those issues tend to surface when Building Control, insurers or future owners get involved, or when the system fails. By then, the original “quick advice” offers no protection to anyone.
Knowing when to push back is not about being awkward. It is part of delivering a proper service.
Most online retailers, and many pump manufacturers, do not hold Professional Indemnity insurance. They are insured for product liability, which covers defects in the product itself, not whether a pump was correctly selected for a specific site.
Product liability does not cover friction loss calculations, pipe sizing decisions or layout assumptions. Recommending site-specific solutions without Professional Indemnity cover would be irresponsible and would leave the customer exposed if something goes wrong.
This is why advice from forums, merchants or manufacturers can sound confident but carries no accountability.
Not all pump advice requires engineering design. Portable pumps that are not permanently installed, such as puddle pumps, can often be discussed at a product level. Likewise, for applications like swimming pools, we provide sizing guidance so customers can undertake the design themselves. Where a client has already designed a system and is asking whether a particular pump is suitable for that defined duty, this is product clarification rather than design. The key difference is whether responsibility for site-specific calculations and system performance is being transferred.
Under the Construction Design and Management Regulations, designers must only undertake work they are competent to deliver, with adequate time and resources. Clients also have duties, including not pushing designers to undertake work for less than it would reasonably cost to do properly. When enquiries come through an online store, that boundary is often blurred. Product sales and engineering design start to merge. The legal duties do not disappear just because the conversation started with a product.
An online store is a retailer. Margins are tight and the model is built around supplying equipment, not absorbing site-specific engineering risk. Even leaving liability aside, it is not commercially viable for bespoke design work to be carried out free of charge.
Where engineering judgement is required, it needs to be scoped, priced and undertaken properly.
Where certainty is needed, the correct route is a defined, design fee or design check. That allows the right calculations to be carried out, assumptions to be stated clearly, and responsibility to sit in the right place.
Where a scheme requires site-specific advice, it is necessary that work sits with a qualified and experienced engineer rather than a sales function, and while we can deliver this through our sister consultancy, FPS Environmental Ltd, it is important that the distinction between product advice and engineering design is recognised and not blurred.
This is not about refusing to help. It is about doing things properly.
Understanding where product advice ends and engineering responsibility begins protects the customer, the installer and the long-term performance of the system.
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A sump pump is an automatic water pump installed in a chamber at the lowest point of a property to collect and remove water when levels rise. Used for flood control, basements, garages and pumped drainage where gravity outfall is not possible, a correctly sized and installed system becomes a reliable, low-intervention water management solution.
