Introduction and definition

This article will analyse the concept of reliance data in EPC Contracts and provide a methodology to identify it. We can define reliance data as follows:

“Reliance data” (also named “rely on data”) is the data identified in an EPC Contract that the EPC Contractor can take for granted. If this data changes during the course of the design or execution of the EPC Contract, a Variation Order should be agreed between the Employer and the EPC Contractor in order to implement the impact on the performance guarantees, the time for completion and the price.

Context in EPC Contract negotiations

The starting point of many EPC tenders and contract negotiations is as follows: the Owner / Employer provides the Contractor with the data he has in his possession regarding the project together with a specific statement that

«the Employer does not give any warranty as to the completeness, accuracy or fitness for purpose»

of that information. He does this to avoid any claim by the Contractor during the project execution on the basis that the provided information is inaccurate or incorrect. Sometimes the situation is even worse and the Owner / Employer simply tries to avoid giving any information.

In practice, withholding information is counterproductive as it does not enable the EPC Contractor to make a proper proposal, with reasonable efforts. Contractors may walk away from the tender, overprice or underestimate the project’s cost. In the latter case, Contractors often create trouble during the execution phase in an attempt to limit their losses.

Reliance data in FIDIC

FIDIC 1999 Silver Book (Clause 5.1) requires the Contractor to scrutinize the Employer’s Requirements prior to the bid submittal. The Employer shall not be responsible for any error, inaccuracy or omission of any kind in the Employer’s Requirements except for data and information which are stated as immutable or the responsibility of the Employer and also except for data and information which cannot be verified by the Contractor. Having some data on which the Contractor may rely (reliance data) is therefore good industry practice and in line with the contract standards.

The difficulty starts when we want to precisely identify the “reliance data”, “baseline data”, “rely on data” or whatever word is defined in the contract to introduce the same concept. The data is usually parked in an appendix containing a limited list of data for which the Employer takes responsibility.

Structured approach to identify rely on data – “black box” concept

During those long contract negotiations, I had some thoughts about a structured approach to identifying reliance data. I came up with a “black box” concept:

  • Look at the project (to be executed) as a “black box”.
  • Whatever is in the box are the works to be executed. These are defined by a functional, not detailed/prescriptive, specification. Certain performance requirements are to be achieved usually by the time of taking-over. The reliance data should not include any information from within the “black box”.
  • On the other hand, this “black box” is somehow connected to and interacting with the environment. It is obviously physically attached to / founded on the outside world. It also receives some inflow. The “black box” can be impacted/shaken-up by the outside environment. The quality, magnitude and characteristics of these foundations, inflows and impacts are data that can, and often should, become reliance data.

Concrete example of identification of reliance data

reliance data

Let’s run this on a concrete example in order to make the “black box” concept more understandable. In the case of building a hydro power plant, the following can be reliance data:

  • Geo-technical baseline data: reference characteristics of subsurface conditions like rock classes (“foundations”)
  • Water quality: chemical composition of water quality for which the penstocks and turbine equipment should be designed; maximum water temperature to be taken into consideration for the design of the cooling system; hydrological data (“inflow”)
  • Grid connection information: data related to the transmission line and grid characteristics (voltage, frequency). The grid often still has to be expanded under a separate contract (“connections”)
  • Maximum wind speed or seismic acceleration coefficient: design requirements that the “black box” will have to withstand (“impacts”).


In conclusion, having some concept of reliance data is healthy for a balanced EPC contract. Both the Employer and the Contractor shall reasonably reflect on this concept and the “black box” approach can be helpful. Jointly, they shall try to minimize the information to those design inputs that are essential and cannot reasonably be verified by the Contractor. This includes information that is

  • the result of long-term data series, or
  • inaccessible, or
  • needing unreasonable efforts and resources to obtain it while the Contractor is not sure to be awarded the contract.

This way, Employers will attract first class Contractors with optimized price levels and avoid conflicts during project execution.

You can find other articles on FIDIC on this blog by clicking here. is the blog on commercial and contractual subjects for the Project Businesses (Construction, Infrastructure, Oil & Gas, Power & Renewable, Water Supply & Sanitation, etc). Its objective is to stimulate reflection, learning, convergence to balanced contracts and positive dispute resolution. You can subscribe to our newsletter by writing to “”. You can also connect to our LinkedIn page. Engagement with the readers is what keeps us going. So, don’t hesitate to exchange with us by commenting here below, liking our publications on LinkedIn and writing to us “”.


Liaqat hayat · 10 March 2018 at 12 h 46 min

EPC ontracts also need to be scrutinised for at tender stage for following
1.the employer requirement given in bid needs to thoroughly checked with the reliance data so worked out
2.the availability of right inputs to be checked with specification during execution and also in commissioning as well as in operation there after

f. solino · 3 April 2018 at 1 h 06 min

Thank you for any other wonderful article. Where else may just anybody get that kind of info in such an ideal method of writing? I’ve a presentation subsequent week, and I am on the search for such information.

Blog on contracts, "", new status after 6 more months - · 7 November 2018 at 19 h 34 min

[…] How to establish reliance data in EPC Contracts (like FIDIC Silver Book)? […]

"EPC or not EPC, that's the question" - · 18 February 2019 at 10 h 41 min

[…] The Contractor collects his own information on how to execute the works. Any information provided by the Employer is “for information only” except for very limited baseline/reliance data. For more details on the concept of reliance data, click here. […]

Rehabilitation and EPC philosophy, are they compatible? - · 24 February 2019 at 21 h 30 min

[…] On rehabilitation projects, the existing configuration/situation has always to be taken into account. During the bidding stage, the Employer usually informs the bidders about the existing situation. He does this by providing the as built drawings and a condition assessment report. Each bidder cannot collect that information himself. This would suppose stopping the equipment, dismantling certain parts and even go beyond a visible inspection. Thus, the Employer has to take the responsibility for the large quantity of information he has provided. We are not in a situation of a limited quantity of “reliance data”. […]

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